[X86][TLI] DAGCombine: Unfold variable bit-clearing mask to two shifts.

Summary:
This adds a reverse transform for the instcombine canonicalizations
that were added in D47980, D47981.

As discussed later, that was worse at least for the code size,
and potentially for the performance, too.

https://rise4fun.com/Alive/Zmpl

Reviewers: craig.topper, RKSimon, spatel

Reviewed By: spatel

Subscribers: reames, llvm-commits

Differential Revision: https://reviews.llvm.org/D48768

llvm-svn: 336585

1 files changed, 297 insertions, 309 deletions

diff --git a/llvm/test/CodeGen/X86/clear-lowbits.ll b/llvm/test/CodeGen/X86/clear-lowbits.ll
index b05478fd7e3..8c9a24ce0c7 100644
--- a/llvm/test/CodeGen/X86/clear-lowbits.ll
+++ b/llvm/test/CodeGen/X86/clear-lowbits.ll
@@ -27,17 +27,18 @@ define i8 @clear_lowbits8_c0(i8 %val, i8 %numlowbits) nounwind {
 ; X86-LABEL: clear_lowbits8_c0:
 ; X86:       # %bb.0:
 ; X86-NEXT:    movb {{[0-9]+}}(%esp), %cl
-; X86-NEXT:    movb $-1, %al
+; X86-NEXT:    movb {{[0-9]+}}(%esp), %al
+; X86-NEXT:    shrb %cl, %al
 ; X86-NEXT:    shlb %cl, %al
-; X86-NEXT:    andb {{[0-9]+}}(%esp), %al
 ; X86-NEXT:    retl
 ;
 ; X64-LABEL: clear_lowbits8_c0:
 ; X64:       # %bb.0:
-; X64-NEXT:    movb $-1, %al
 ; X64-NEXT:    movl %esi, %ecx
-; X64-NEXT:    shlb %cl, %al
-; X64-NEXT:    andb %dil, %al
+; X64-NEXT:    shrb %cl, %dil
+; X64-NEXT:    # kill: def $cl killed $cl killed $ecx
+; X64-NEXT:    shlb %cl, %dil
+; X64-NEXT:    movl %edi, %eax
 ; X64-NEXT:    retq
   %mask = shl i8 -1, %numlowbits
   %masked = and i8 %mask, %val
@@ -47,19 +48,20 @@ define i8 @clear_lowbits8_c0(i8 %val, i8 %numlowbits) nounwind {
 define i8 @clear_lowbits8_c2_load(i8* %w, i8 %numlowbits) nounwind {
 ; X86-LABEL: clear_lowbits8_c2_load:
 ; X86:       # %bb.0:
-; X86-NEXT:    movl {{[0-9]+}}(%esp), %edx
 ; X86-NEXT:    movb {{[0-9]+}}(%esp), %cl
-; X86-NEXT:    movb $-1, %al
+; X86-NEXT:    movl {{[0-9]+}}(%esp), %eax
+; X86-NEXT:    movb (%eax), %al
+; X86-NEXT:    shrb %cl, %al
 ; X86-NEXT:    shlb %cl, %al
-; X86-NEXT:    andb (%edx), %al
 ; X86-NEXT:    retl
 ;
 ; X64-LABEL: clear_lowbits8_c2_load:
 ; X64:       # %bb.0:
-; X64-NEXT:    movb $-1, %al
 ; X64-NEXT:    movl %esi, %ecx
+; X64-NEXT:    movb (%rdi), %al
+; X64-NEXT:    shrb %cl, %al
+; X64-NEXT:    # kill: def $cl killed $cl killed $ecx
 ; X64-NEXT:    shlb %cl, %al
-; X64-NEXT:    andb (%rdi), %al
 ; X64-NEXT:    retq
   %val = load i8, i8* %w
   %mask = shl i8 -1, %numlowbits
@@ -71,17 +73,18 @@ define i8 @clear_lowbits8_c4_commutative(i8 %val, i8 %numlowbits) nounwind {
 ; X86-LABEL: clear_lowbits8_c4_commutative:
 ; X86:       # %bb.0:
 ; X86-NEXT:    movb {{[0-9]+}}(%esp), %cl
-; X86-NEXT:    movb $-1, %al
+; X86-NEXT:    movb {{[0-9]+}}(%esp), %al
+; X86-NEXT:    shrb %cl, %al
 ; X86-NEXT:    shlb %cl, %al
-; X86-NEXT:    andb {{[0-9]+}}(%esp), %al
 ; X86-NEXT:    retl
 ;
 ; X64-LABEL: clear_lowbits8_c4_commutative:
 ; X64:       # %bb.0:
-; X64-NEXT:    movb $-1, %al
 ; X64-NEXT:    movl %esi, %ecx
-; X64-NEXT:    shlb %cl, %al
-; X64-NEXT:    andb %dil, %al
+; X64-NEXT:    shrb %cl, %dil
+; X64-NEXT:    # kill: def $cl killed $cl killed $ecx
+; X64-NEXT:    shlb %cl, %dil
+; X64-NEXT:    movl %edi, %eax
 ; X64-NEXT:    retq
   %mask = shl i8 -1, %numlowbits
   %masked = and i8 %val, %mask ; swapped order
@@ -94,35 +97,36 @@ define i16 @clear_lowbits16_c0(i16 %val, i16 %numlowbits) nounwind {
 ; X86-NOBMI2-LABEL: clear_lowbits16_c0:
 ; X86-NOBMI2:       # %bb.0:
 ; X86-NOBMI2-NEXT:    movb {{[0-9]+}}(%esp), %cl
-; X86-NOBMI2-NEXT:    movl $-1, %eax
+; X86-NOBMI2-NEXT:    movzwl {{[0-9]+}}(%esp), %eax
+; X86-NOBMI2-NEXT:    shrl %cl, %eax
 ; X86-NOBMI2-NEXT:    shll %cl, %eax
-; X86-NOBMI2-NEXT:    andw {{[0-9]+}}(%esp), %ax
 ; X86-NOBMI2-NEXT:    # kill: def $ax killed $ax killed $eax
 ; X86-NOBMI2-NEXT:    retl
 ;
 ; X86-BMI2-LABEL: clear_lowbits16_c0:
 ; X86-BMI2:       # %bb.0:
-; X86-BMI2-NEXT:    movb {{[0-9]+}}(%esp), %al
-; X86-BMI2-NEXT:    movl $-1, %ecx
-; X86-BMI2-NEXT:    shlxl %eax, %ecx, %eax
-; X86-BMI2-NEXT:    andw {{[0-9]+}}(%esp), %ax
+; X86-BMI2-NEXT:    movzwl {{[0-9]+}}(%esp), %eax
+; X86-BMI2-NEXT:    movb {{[0-9]+}}(%esp), %cl
+; X86-BMI2-NEXT:    shrxl %ecx, %eax, %eax
+; X86-BMI2-NEXT:    shlxl %ecx, %eax, %eax
 ; X86-BMI2-NEXT:    # kill: def $ax killed $ax killed $eax
 ; X86-BMI2-NEXT:    retl
 ;
 ; X64-NOBMI2-LABEL: clear_lowbits16_c0:
 ; X64-NOBMI2:       # %bb.0:
-; X64-NOBMI2-NEXT:    movl $-1, %eax
 ; X64-NOBMI2-NEXT:    movl %esi, %ecx
+; X64-NOBMI2-NEXT:    movzwl %di, %eax
+; X64-NOBMI2-NEXT:    shrl %cl, %eax
+; X64-NOBMI2-NEXT:    # kill: def $cl killed $cl killed $ecx
 ; X64-NOBMI2-NEXT:    shll %cl, %eax
-; X64-NOBMI2-NEXT:    andl %edi, %eax
 ; X64-NOBMI2-NEXT:    # kill: def $ax killed $ax killed $eax
 ; X64-NOBMI2-NEXT:    retq
 ;
 ; X64-BMI2-LABEL: clear_lowbits16_c0:
 ; X64-BMI2:       # %bb.0:
-; X64-BMI2-NEXT:    movl $-1, %eax
+; X64-BMI2-NEXT:    movzwl %di, %eax
+; X64-BMI2-NEXT:    shrxl %esi, %eax, %eax
 ; X64-BMI2-NEXT:    shlxl %esi, %eax, %eax
-; X64-BMI2-NEXT:    andl %edi, %eax
 ; X64-BMI2-NEXT:    # kill: def $ax killed $ax killed $eax
 ; X64-BMI2-NEXT:    retq
   %mask = shl i16 -1, %numlowbits
@@ -134,35 +138,36 @@ define i16 @clear_lowbits16_c1_indexzext(i16 %val, i8 %numlowbits) nounwind {
 ; X86-NOBMI2-LABEL: clear_lowbits16_c1_indexzext:
 ; X86-NOBMI2:       # %bb.0:
 ; X86-NOBMI2-NEXT:    movb {{[0-9]+}}(%esp), %cl
-; X86-NOBMI2-NEXT:    movl $-1, %eax
+; X86-NOBMI2-NEXT:    movzwl {{[0-9]+}}(%esp), %eax
+; X86-NOBMI2-NEXT:    shrl %cl, %eax
 ; X86-NOBMI2-NEXT:    shll %cl, %eax
-; X86-NOBMI2-NEXT:    andw {{[0-9]+}}(%esp), %ax
 ; X86-NOBMI2-NEXT:    # kill: def $ax killed $ax killed $eax
 ; X86-NOBMI2-NEXT:    retl
 ;
 ; X86-BMI2-LABEL: clear_lowbits16_c1_indexzext:
 ; X86-BMI2:       # %bb.0:
-; X86-BMI2-NEXT:    movb {{[0-9]+}}(%esp), %al
-; X86-BMI2-NEXT:    movl $-1, %ecx
-; X86-BMI2-NEXT:    shlxl %eax, %ecx, %eax
-; X86-BMI2-NEXT:    andw {{[0-9]+}}(%esp), %ax
+; X86-BMI2-NEXT:    movzwl {{[0-9]+}}(%esp), %eax
+; X86-BMI2-NEXT:    movb {{[0-9]+}}(%esp), %cl
+; X86-BMI2-NEXT:    shrxl %ecx, %eax, %eax
+; X86-BMI2-NEXT:    shlxl %ecx, %eax, %eax
 ; X86-BMI2-NEXT:    # kill: def $ax killed $ax killed $eax
 ; X86-BMI2-NEXT:    retl
 ;
 ; X64-NOBMI2-LABEL: clear_lowbits16_c1_indexzext:
 ; X64-NOBMI2:       # %bb.0:
-; X64-NOBMI2-NEXT:    movl $-1, %eax
 ; X64-NOBMI2-NEXT:    movl %esi, %ecx
+; X64-NOBMI2-NEXT:    movzwl %di, %eax
+; X64-NOBMI2-NEXT:    shrl %cl, %eax
+; X64-NOBMI2-NEXT:    # kill: def $cl killed $cl killed $ecx
 ; X64-NOBMI2-NEXT:    shll %cl, %eax
-; X64-NOBMI2-NEXT:    andl %edi, %eax
 ; X64-NOBMI2-NEXT:    # kill: def $ax killed $ax killed $eax
 ; X64-NOBMI2-NEXT:    retq
 ;
 ; X64-BMI2-LABEL: clear_lowbits16_c1_indexzext:
 ; X64-BMI2:       # %bb.0:
-; X64-BMI2-NEXT:    movl $-1, %eax
+; X64-BMI2-NEXT:    movzwl %di, %eax
+; X64-BMI2-NEXT:    shrxl %esi, %eax, %eax
 ; X64-BMI2-NEXT:    shlxl %esi, %eax, %eax
-; X64-BMI2-NEXT:    andl %edi, %eax
 ; X64-BMI2-NEXT:    # kill: def $ax killed $ax killed $eax
 ; X64-BMI2-NEXT:    retq
   %sh_prom = zext i8 %numlowbits to i16
@@ -174,38 +179,39 @@ define i16 @clear_lowbits16_c1_indexzext(i16 %val, i8 %numlowbits) nounwind {
 define i16 @clear_lowbits16_c2_load(i16* %w, i16 %numlowbits) nounwind {
 ; X86-NOBMI2-LABEL: clear_lowbits16_c2_load:
 ; X86-NOBMI2:       # %bb.0:
-; X86-NOBMI2-NEXT:    movl {{[0-9]+}}(%esp), %edx
 ; X86-NOBMI2-NEXT:    movb {{[0-9]+}}(%esp), %cl
-; X86-NOBMI2-NEXT:    movl $-1, %eax
+; X86-NOBMI2-NEXT:    movl {{[0-9]+}}(%esp), %eax
+; X86-NOBMI2-NEXT:    movzwl (%eax), %eax
+; X86-NOBMI2-NEXT:    shrl %cl, %eax
 ; X86-NOBMI2-NEXT:    shll %cl, %eax
-; X86-NOBMI2-NEXT:    andw (%edx), %ax
 ; X86-NOBMI2-NEXT:    # kill: def $ax killed $ax killed $eax
 ; X86-NOBMI2-NEXT:    retl
 ;
 ; X86-BMI2-LABEL: clear_lowbits16_c2_load:
 ; X86-BMI2:       # %bb.0:
-; X86-BMI2-NEXT:    movl {{[0-9]+}}(%esp), %ecx
 ; X86-BMI2-NEXT:    movb {{[0-9]+}}(%esp), %al
-; X86-BMI2-NEXT:    movl $-1, %edx
-; X86-BMI2-NEXT:    shlxl %eax, %edx, %eax
-; X86-BMI2-NEXT:    andw (%ecx), %ax
+; X86-BMI2-NEXT:    movl {{[0-9]+}}(%esp), %ecx
+; X86-BMI2-NEXT:    movzwl (%ecx), %ecx
+; X86-BMI2-NEXT:    shrxl %eax, %ecx, %ecx
+; X86-BMI2-NEXT:    shlxl %eax, %ecx, %eax
 ; X86-BMI2-NEXT:    # kill: def $ax killed $ax killed $eax
 ; X86-BMI2-NEXT:    retl
 ;
 ; X64-NOBMI2-LABEL: clear_lowbits16_c2_load:
 ; X64-NOBMI2:       # %bb.0:
-; X64-NOBMI2-NEXT:    movl $-1, %eax
 ; X64-NOBMI2-NEXT:    movl %esi, %ecx
+; X64-NOBMI2-NEXT:    movzwl (%rdi), %eax
+; X64-NOBMI2-NEXT:    shrl %cl, %eax
+; X64-NOBMI2-NEXT:    # kill: def $cl killed $cl killed $ecx
 ; X64-NOBMI2-NEXT:    shll %cl, %eax
-; X64-NOBMI2-NEXT:    andw (%rdi), %ax
 ; X64-NOBMI2-NEXT:    # kill: def $ax killed $ax killed $eax
 ; X64-NOBMI2-NEXT:    retq
 ;
 ; X64-BMI2-LABEL: clear_lowbits16_c2_load:
 ; X64-BMI2:       # %bb.0:
-; X64-BMI2-NEXT:    movl $-1, %eax
+; X64-BMI2-NEXT:    movzwl (%rdi), %eax
+; X64-BMI2-NEXT:    shrxl %esi, %eax, %eax
 ; X64-BMI2-NEXT:    shlxl %esi, %eax, %eax
-; X64-BMI2-NEXT:    andw (%rdi), %ax
 ; X64-BMI2-NEXT:    # kill: def $ax killed $ax killed $eax
 ; X64-BMI2-NEXT:    retq
   %val = load i16, i16* %w
@@ -217,38 +223,39 @@ define i16 @clear_lowbits16_c2_load(i16* %w, i16 %numlowbits) nounwind {
 define i16 @clear_lowbits16_c3_load_indexzext(i16* %w, i8 %numlowbits) nounwind {
 ; X86-NOBMI2-LABEL: clear_lowbits16_c3_load_indexzext:
 ; X86-NOBMI2:       # %bb.0:
-; X86-NOBMI2-NEXT:    movl {{[0-9]+}}(%esp), %edx
 ; X86-NOBMI2-NEXT:    movb {{[0-9]+}}(%esp), %cl
-; X86-NOBMI2-NEXT:    movl $-1, %eax
+; X86-NOBMI2-NEXT:    movl {{[0-9]+}}(%esp), %eax
+; X86-NOBMI2-NEXT:    movzwl (%eax), %eax
+; X86-NOBMI2-NEXT:    shrl %cl, %eax
 ; X86-NOBMI2-NEXT:    shll %cl, %eax
-; X86-NOBMI2-NEXT:    andw (%edx), %ax
 ; X86-NOBMI2-NEXT:    # kill: def $ax killed $ax killed $eax
 ; X86-NOBMI2-NEXT:    retl
 ;
 ; X86-BMI2-LABEL: clear_lowbits16_c3_load_indexzext:
 ; X86-BMI2:       # %bb.0:
-; X86-BMI2-NEXT:    movl {{[0-9]+}}(%esp), %ecx
 ; X86-BMI2-NEXT:    movb {{[0-9]+}}(%esp), %al
-; X86-BMI2-NEXT:    movl $-1, %edx
-; X86-BMI2-NEXT:    shlxl %eax, %edx, %eax
-; X86-BMI2-NEXT:    andw (%ecx), %ax
+; X86-BMI2-NEXT:    movl {{[0-9]+}}(%esp), %ecx
+; X86-BMI2-NEXT:    movzwl (%ecx), %ecx
+; X86-BMI2-NEXT:    shrxl %eax, %ecx, %ecx
+; X86-BMI2-NEXT:    shlxl %eax, %ecx, %eax
 ; X86-BMI2-NEXT:    # kill: def $ax killed $ax killed $eax
 ; X86-BMI2-NEXT:    retl
 ;
 ; X64-NOBMI2-LABEL: clear_lowbits16_c3_load_indexzext:
 ; X64-NOBMI2:       # %bb.0:
-; X64-NOBMI2-NEXT:    movl $-1, %eax
 ; X64-NOBMI2-NEXT:    movl %esi, %ecx
+; X64-NOBMI2-NEXT:    movzwl (%rdi), %eax
+; X64-NOBMI2-NEXT:    shrl %cl, %eax
+; X64-NOBMI2-NEXT:    # kill: def $cl killed $cl killed $ecx
 ; X64-NOBMI2-NEXT:    shll %cl, %eax
-; X64-NOBMI2-NEXT:    andw (%rdi), %ax
 ; X64-NOBMI2-NEXT:    # kill: def $ax killed $ax killed $eax
 ; X64-NOBMI2-NEXT:    retq
 ;
 ; X64-BMI2-LABEL: clear_lowbits16_c3_load_indexzext:
 ; X64-BMI2:       # %bb.0:
-; X64-BMI2-NEXT:    movl $-1, %eax
+; X64-BMI2-NEXT:    movzwl (%rdi), %eax
+; X64-BMI2-NEXT:    shrxl %esi, %eax, %eax
 ; X64-BMI2-NEXT:    shlxl %esi, %eax, %eax
-; X64-BMI2-NEXT:    andw (%rdi), %ax
 ; X64-BMI2-NEXT:    # kill: def $ax killed $ax killed $eax
 ; X64-BMI2-NEXT:    retq
   %val = load i16, i16* %w
@@ -262,35 +269,36 @@ define i16 @clear_lowbits16_c4_commutative(i16 %val, i16 %numlowbits) nounwind {
 ; X86-NOBMI2-LABEL: clear_lowbits16_c4_commutative:
 ; X86-NOBMI2:       # %bb.0:
 ; X86-NOBMI2-NEXT:    movb {{[0-9]+}}(%esp), %cl
-; X86-NOBMI2-NEXT:    movl $-1, %eax
+; X86-NOBMI2-NEXT:    movzwl {{[0-9]+}}(%esp), %eax
+; X86-NOBMI2-NEXT:    shrl %cl, %eax
 ; X86-NOBMI2-NEXT:    shll %cl, %eax
-; X86-NOBMI2-NEXT:    andw {{[0-9]+}}(%esp), %ax
 ; X86-NOBMI2-NEXT:    # kill: def $ax killed $ax killed $eax
 ; X86-NOBMI2-NEXT:    retl
 ;
 ; X86-BMI2-LABEL: clear_lowbits16_c4_commutative:
 ; X86-BMI2:       # %bb.0:
-; X86-BMI2-NEXT:    movb {{[0-9]+}}(%esp), %al
-; X86-BMI2-NEXT:    movl $-1, %ecx
-; X86-BMI2-NEXT:    shlxl %eax, %ecx, %eax
-; X86-BMI2-NEXT:    andw {{[0-9]+}}(%esp), %ax
+; X86-BMI2-NEXT:    movzwl {{[0-9]+}}(%esp), %eax
+; X86-BMI2-NEXT:    movb {{[0-9]+}}(%esp), %cl
+; X86-BMI2-NEXT:    shrxl %ecx, %eax, %eax
+; X86-BMI2-NEXT:    shlxl %ecx, %eax, %eax
 ; X86-BMI2-NEXT:    # kill: def $ax killed $ax killed $eax
 ; X86-BMI2-NEXT:    retl
 ;
 ; X64-NOBMI2-LABEL: clear_lowbits16_c4_commutative:
 ; X64-NOBMI2:       # %bb.0:
-; X64-NOBMI2-NEXT:    movl $-1, %eax
 ; X64-NOBMI2-NEXT:    movl %esi, %ecx
+; X64-NOBMI2-NEXT:    movzwl %di, %eax
+; X64-NOBMI2-NEXT:    shrl %cl, %eax
+; X64-NOBMI2-NEXT:    # kill: def $cl killed $cl killed $ecx
 ; X64-NOBMI2-NEXT:    shll %cl, %eax
-; X64-NOBMI2-NEXT:    andl %edi, %eax
 ; X64-NOBMI2-NEXT:    # kill: def $ax killed $ax killed $eax
 ; X64-NOBMI2-NEXT:    retq
 ;
 ; X64-BMI2-LABEL: clear_lowbits16_c4_commutative:
 ; X64-BMI2:       # %bb.0:
-; X64-BMI2-NEXT:    movl $-1, %eax
+; X64-BMI2-NEXT:    movzwl %di, %eax
+; X64-BMI2-NEXT:    shrxl %esi, %eax, %eax
 ; X64-BMI2-NEXT:    shlxl %esi, %eax, %eax
-; X64-BMI2-NEXT:    andl %edi, %eax
 ; X64-BMI2-NEXT:    # kill: def $ax killed $ax killed $eax
 ; X64-BMI2-NEXT:    retq
   %mask = shl i16 -1, %numlowbits
@@ -304,32 +312,31 @@ define i32 @clear_lowbits32_c0(i32 %val, i32 %numlowbits) nounwind {
 ; X86-NOBMI2-LABEL: clear_lowbits32_c0:
 ; X86-NOBMI2:       # %bb.0:
 ; X86-NOBMI2-NEXT:    movb {{[0-9]+}}(%esp), %cl
-; X86-NOBMI2-NEXT:    movl $-1, %eax
+; X86-NOBMI2-NEXT:    movl {{[0-9]+}}(%esp), %eax
+; X86-NOBMI2-NEXT:    shrl %cl, %eax
 ; X86-NOBMI2-NEXT:    shll %cl, %eax
-; X86-NOBMI2-NEXT:    andl {{[0-9]+}}(%esp), %eax
 ; X86-NOBMI2-NEXT:    retl
 ;
 ; X86-BMI2-LABEL: clear_lowbits32_c0:
 ; X86-BMI2:       # %bb.0:
 ; X86-BMI2-NEXT:    movb {{[0-9]+}}(%esp), %al
-; X86-BMI2-NEXT:    movl $-1, %ecx
+; X86-BMI2-NEXT:    shrxl %eax, {{[0-9]+}}(%esp), %ecx
 ; X86-BMI2-NEXT:    shlxl %eax, %ecx, %eax
-; X86-BMI2-NEXT:    andl {{[0-9]+}}(%esp), %eax
 ; X86-BMI2-NEXT:    retl
 ;
 ; X64-NOBMI2-LABEL: clear_lowbits32_c0:
 ; X64-NOBMI2:       # %bb.0:
-; X64-NOBMI2-NEXT:    movl $-1, %eax
 ; X64-NOBMI2-NEXT:    movl %esi, %ecx
-; X64-NOBMI2-NEXT:    shll %cl, %eax
-; X64-NOBMI2-NEXT:    andl %edi, %eax
+; X64-NOBMI2-NEXT:    shrl %cl, %edi
+; X64-NOBMI2-NEXT:    # kill: def $cl killed $cl killed $ecx
+; X64-NOBMI2-NEXT:    shll %cl, %edi
+; X64-NOBMI2-NEXT:    movl %edi, %eax
 ; X64-NOBMI2-NEXT:    retq
 ;
 ; X64-BMI2-LABEL: clear_lowbits32_c0:
 ; X64-BMI2:       # %bb.0:
-; X64-BMI2-NEXT:    movl $-1, %eax
+; X64-BMI2-NEXT:    shrxl %esi, %edi, %eax
 ; X64-BMI2-NEXT:    shlxl %esi, %eax, %eax
-; X64-BMI2-NEXT:    andl %edi, %eax
 ; X64-BMI2-NEXT:    retq
   %mask = shl i32 -1, %numlowbits
   %masked = and i32 %mask, %val
@@ -340,32 +347,31 @@ define i32 @clear_lowbits32_c1_indexzext(i32 %val, i8 %numlowbits) nounwind {
 ; X86-NOBMI2-LABEL: clear_lowbits32_c1_indexzext:
 ; X86-NOBMI2:       # %bb.0:
 ; X86-NOBMI2-NEXT:    movb {{[0-9]+}}(%esp), %cl
-; X86-NOBMI2-NEXT:    movl $-1, %eax
+; X86-NOBMI2-NEXT:    movl {{[0-9]+}}(%esp), %eax
+; X86-NOBMI2-NEXT:    shrl %cl, %eax
 ; X86-NOBMI2-NEXT:    shll %cl, %eax
-; X86-NOBMI2-NEXT:    andl {{[0-9]+}}(%esp), %eax
 ; X86-NOBMI2-NEXT:    retl
 ;
 ; X86-BMI2-LABEL: clear_lowbits32_c1_indexzext:
 ; X86-BMI2:       # %bb.0:
 ; X86-BMI2-NEXT:    movb {{[0-9]+}}(%esp), %al
-; X86-BMI2-NEXT:    movl $-1, %ecx
+; X86-BMI2-NEXT:    shrxl %eax, {{[0-9]+}}(%esp), %ecx
 ; X86-BMI2-NEXT:    shlxl %eax, %ecx, %eax
-; X86-BMI2-NEXT:    andl {{[0-9]+}}(%esp), %eax
 ; X86-BMI2-NEXT:    retl
 ;
 ; X64-NOBMI2-LABEL: clear_lowbits32_c1_indexzext:
 ; X64-NOBMI2:       # %bb.0:
-; X64-NOBMI2-NEXT:    movl $-1, %eax
 ; X64-NOBMI2-NEXT:    movl %esi, %ecx
-; X64-NOBMI2-NEXT:    shll %cl, %eax
-; X64-NOBMI2-NEXT:    andl %edi, %eax
+; X64-NOBMI2-NEXT:    shrl %cl, %edi
+; X64-NOBMI2-NEXT:    # kill: def $cl killed $cl killed $ecx
+; X64-NOBMI2-NEXT:    shll %cl, %edi
+; X64-NOBMI2-NEXT:    movl %edi, %eax
 ; X64-NOBMI2-NEXT:    retq
 ;
 ; X64-BMI2-LABEL: clear_lowbits32_c1_indexzext:
 ; X64-BMI2:       # %bb.0:
-; X64-BMI2-NEXT:    movl $-1, %eax
+; X64-BMI2-NEXT:    shrxl %esi, %edi, %eax
 ; X64-BMI2-NEXT:    shlxl %esi, %eax, %eax
-; X64-BMI2-NEXT:    andl %edi, %eax
 ; X64-BMI2-NEXT:    retq
   %sh_prom = zext i8 %numlowbits to i32
   %mask = shl i32 -1, %sh_prom
@@ -376,35 +382,34 @@ define i32 @clear_lowbits32_c1_indexzext(i32 %val, i8 %numlowbits) nounwind {
 define i32 @clear_lowbits32_c2_load(i32* %w, i32 %numlowbits) nounwind {
 ; X86-NOBMI2-LABEL: clear_lowbits32_c2_load:
 ; X86-NOBMI2:       # %bb.0:
-; X86-NOBMI2-NEXT:    movl {{[0-9]+}}(%esp), %edx
 ; X86-NOBMI2-NEXT:    movb {{[0-9]+}}(%esp), %cl
-; X86-NOBMI2-NEXT:    movl $-1, %eax
+; X86-NOBMI2-NEXT:    movl {{[0-9]+}}(%esp), %eax
+; X86-NOBMI2-NEXT:    movl (%eax), %eax
+; X86-NOBMI2-NEXT:    shrl %cl, %eax
 ; X86-NOBMI2-NEXT:    shll %cl, %eax
-; X86-NOBMI2-NEXT:    andl (%edx), %eax
 ; X86-NOBMI2-NEXT:    retl
 ;
 ; X86-BMI2-LABEL: clear_lowbits32_c2_load:
 ; X86-BMI2:       # %bb.0:
-; X86-BMI2-NEXT:    movl {{[0-9]+}}(%esp), %ecx
-; X86-BMI2-NEXT:    movb {{[0-9]+}}(%esp), %al
-; X86-BMI2-NEXT:    movl $-1, %edx
-; X86-BMI2-NEXT:    shlxl %eax, %edx, %eax
-; X86-BMI2-NEXT:    andl (%ecx), %eax
+; X86-BMI2-NEXT:    movl {{[0-9]+}}(%esp), %eax
+; X86-BMI2-NEXT:    movb {{[0-9]+}}(%esp), %cl
+; X86-BMI2-NEXT:    shrxl %ecx, (%eax), %eax
+; X86-BMI2-NEXT:    shlxl %ecx, %eax, %eax
 ; X86-BMI2-NEXT:    retl
 ;
 ; X64-NOBMI2-LABEL: clear_lowbits32_c2_load:
 ; X64-NOBMI2:       # %bb.0:
-; X64-NOBMI2-NEXT:    movl $-1, %eax
 ; X64-NOBMI2-NEXT:    movl %esi, %ecx
+; X64-NOBMI2-NEXT:    movl (%rdi), %eax
+; X64-NOBMI2-NEXT:    shrl %cl, %eax
+; X64-NOBMI2-NEXT:    # kill: def $cl killed $cl killed $ecx
 ; X64-NOBMI2-NEXT:    shll %cl, %eax
-; X64-NOBMI2-NEXT:    andl (%rdi), %eax
 ; X64-NOBMI2-NEXT:    retq
 ;
 ; X64-BMI2-LABEL: clear_lowbits32_c2_load:
 ; X64-BMI2:       # %bb.0:
-; X64-BMI2-NEXT:    movl $-1, %eax
+; X64-BMI2-NEXT:    shrxl %esi, (%rdi), %eax
 ; X64-BMI2-NEXT:    shlxl %esi, %eax, %eax
-; X64-BMI2-NEXT:    andl (%rdi), %eax
 ; X64-BMI2-NEXT:    retq
   %val = load i32, i32* %w
   %mask = shl i32 -1, %numlowbits
@@ -415,35 +420,34 @@ define i32 @clear_lowbits32_c2_load(i32* %w, i32 %numlowbits) nounwind {
 define i32 @clear_lowbits32_c3_load_indexzext(i32* %w, i8 %numlowbits) nounwind {
 ; X86-NOBMI2-LABEL: clear_lowbits32_c3_load_indexzext:
 ; X86-NOBMI2:       # %bb.0:
-; X86-NOBMI2-NEXT:    movl {{[0-9]+}}(%esp), %edx
 ; X86-NOBMI2-NEXT:    movb {{[0-9]+}}(%esp), %cl
-; X86-NOBMI2-NEXT:    movl $-1, %eax
+; X86-NOBMI2-NEXT:    movl {{[0-9]+}}(%esp), %eax
+; X86-NOBMI2-NEXT:    movl (%eax), %eax
+; X86-NOBMI2-NEXT:    shrl %cl, %eax
 ; X86-NOBMI2-NEXT:    shll %cl, %eax
-; X86-NOBMI2-NEXT:    andl (%edx), %eax
 ; X86-NOBMI2-NEXT:    retl
 ;
 ; X86-BMI2-LABEL: clear_lowbits32_c3_load_indexzext:
 ; X86-BMI2:       # %bb.0:
-; X86-BMI2-NEXT:    movl {{[0-9]+}}(%esp), %ecx
-; X86-BMI2-NEXT:    movb {{[0-9]+}}(%esp), %al
-; X86-BMI2-NEXT:    movl $-1, %edx
-; X86-BMI2-NEXT:    shlxl %eax, %edx, %eax
-; X86-BMI2-NEXT:    andl (%ecx), %eax
+; X86-BMI2-NEXT:    movl {{[0-9]+}}(%esp), %eax
+; X86-BMI2-NEXT:    movb {{[0-9]+}}(%esp), %cl
+; X86-BMI2-NEXT:    shrxl %ecx, (%eax), %eax
+; X86-BMI2-NEXT:    shlxl %ecx, %eax, %eax
 ; X86-BMI2-NEXT:    retl
 ;
 ; X64-NOBMI2-LABEL: clear_lowbits32_c3_load_indexzext:
 ; X64-NOBMI2:       # %bb.0:
-; X64-NOBMI2-NEXT:    movl $-1, %eax
 ; X64-NOBMI2-NEXT:    movl %esi, %ecx
+; X64-NOBMI2-NEXT:    movl (%rdi), %eax
+; X64-NOBMI2-NEXT:    shrl %cl, %eax
+; X64-NOBMI2-NEXT:    # kill: def $cl killed $cl killed $ecx
 ; X64-NOBMI2-NEXT:    shll %cl, %eax
-; X64-NOBMI2-NEXT:    andl (%rdi), %eax
 ; X64-NOBMI2-NEXT:    retq
 ;
 ; X64-BMI2-LABEL: clear_lowbits32_c3_load_indexzext:
 ; X64-BMI2:       # %bb.0:
-; X64-BMI2-NEXT:    movl $-1, %eax
+; X64-BMI2-NEXT:    shrxl %esi, (%rdi), %eax
 ; X64-BMI2-NEXT:    shlxl %esi, %eax, %eax
-; X64-BMI2-NEXT:    andl (%rdi), %eax
 ; X64-BMI2-NEXT:    retq
   %val = load i32, i32* %w
   %sh_prom = zext i8 %numlowbits to i32
@@ -456,32 +460,31 @@ define i32 @clear_lowbits32_c4_commutative(i32 %val, i32 %numlowbits) nounwind {
 ; X86-NOBMI2-LABEL: clear_lowbits32_c4_commutative:
 ; X86-NOBMI2:       # %bb.0:
 ; X86-NOBMI2-NEXT:    movb {{[0-9]+}}(%esp), %cl
-; X86-NOBMI2-NEXT:    movl $-1, %eax
+; X86-NOBMI2-NEXT:    movl {{[0-9]+}}(%esp), %eax
+; X86-NOBMI2-NEXT:    shrl %cl, %eax
 ; X86-NOBMI2-NEXT:    shll %cl, %eax
-; X86-NOBMI2-NEXT:    andl {{[0-9]+}}(%esp), %eax
 ; X86-NOBMI2-NEXT:    retl
 ;
 ; X86-BMI2-LABEL: clear_lowbits32_c4_commutative:
 ; X86-BMI2:       # %bb.0:
 ; X86-BMI2-NEXT:    movb {{[0-9]+}}(%esp), %al
-; X86-BMI2-NEXT:    movl $-1, %ecx
+; X86-BMI2-NEXT:    shrxl %eax, {{[0-9]+}}(%esp), %ecx
 ; X86-BMI2-NEXT:    shlxl %eax, %ecx, %eax
-; X86-BMI2-NEXT:    andl {{[0-9]+}}(%esp), %eax
 ; X86-BMI2-NEXT:    retl
 ;
 ; X64-NOBMI2-LABEL: clear_lowbits32_c4_commutative:
 ; X64-NOBMI2:       # %bb.0:
-; X64-NOBMI2-NEXT:    movl $-1, %eax
 ; X64-NOBMI2-NEXT:    movl %esi, %ecx
-; X64-NOBMI2-NEXT:    shll %cl, %eax
-; X64-NOBMI2-NEXT:    andl %edi, %eax
+; X64-NOBMI2-NEXT:    shrl %cl, %edi
+; X64-NOBMI2-NEXT:    # kill: def $cl killed $cl killed $ecx
+; X64-NOBMI2-NEXT:    shll %cl, %edi
+; X64-NOBMI2-NEXT:    movl %edi, %eax
 ; X64-NOBMI2-NEXT:    retq
 ;
 ; X64-BMI2-LABEL: clear_lowbits32_c4_commutative:
 ; X64-BMI2:       # %bb.0:
-; X64-BMI2-NEXT:    movl $-1, %eax
+; X64-BMI2-NEXT:    shrxl %esi, %edi, %eax
 ; X64-BMI2-NEXT:    shlxl %esi, %eax, %eax
-; X64-BMI2-NEXT:    andl %edi, %eax
 ; X64-BMI2-NEXT:    retq
   %mask = shl i32 -1, %numlowbits
   %masked = and i32 %val, %mask ; swapped order
@@ -526,17 +529,17 @@ define i64 @clear_lowbits64_c0(i64 %val, i64 %numlowbits) nounwind {
 ;
 ; X64-NOBMI2-LABEL: clear_lowbits64_c0:
 ; X64-NOBMI2:       # %bb.0:
-; X64-NOBMI2-NEXT:    movq $-1, %rax
-; X64-NOBMI2-NEXT:    movl %esi, %ecx
-; X64-NOBMI2-NEXT:    shlq %cl, %rax
-; X64-NOBMI2-NEXT:    andq %rdi, %rax
+; X64-NOBMI2-NEXT:    movq %rsi, %rcx
+; X64-NOBMI2-NEXT:    shrq %cl, %rdi
+; X64-NOBMI2-NEXT:    # kill: def $cl killed $cl killed $rcx
+; X64-NOBMI2-NEXT:    shlq %cl, %rdi
+; X64-NOBMI2-NEXT:    movq %rdi, %rax
 ; X64-NOBMI2-NEXT:    retq
 ;
 ; X64-BMI2-LABEL: clear_lowbits64_c0:
 ; X64-BMI2:       # %bb.0:
-; X64-BMI2-NEXT:    movq $-1, %rax
+; X64-BMI2-NEXT:    shrxq %rsi, %rdi, %rax
 ; X64-BMI2-NEXT:    shlxq %rsi, %rax, %rax
-; X64-BMI2-NEXT:    andq %rdi, %rax
 ; X64-BMI2-NEXT:    retq
   %mask = shl i64 -1, %numlowbits
   %masked = and i64 %mask, %val
@@ -579,18 +582,18 @@ define i64 @clear_lowbits64_c1_indexzext(i64 %val, i8 %numlowbits) nounwind {
 ;
 ; X64-NOBMI2-LABEL: clear_lowbits64_c1_indexzext:
 ; X64-NOBMI2:       # %bb.0:
-; X64-NOBMI2-NEXT:    movq $-1, %rax
 ; X64-NOBMI2-NEXT:    movl %esi, %ecx
-; X64-NOBMI2-NEXT:    shlq %cl, %rax
-; X64-NOBMI2-NEXT:    andq %rdi, %rax
+; X64-NOBMI2-NEXT:    shrq %cl, %rdi
+; X64-NOBMI2-NEXT:    # kill: def $cl killed $cl killed $ecx
+; X64-NOBMI2-NEXT:    shlq %cl, %rdi
+; X64-NOBMI2-NEXT:    movq %rdi, %rax
 ; X64-NOBMI2-NEXT:    retq
 ;
 ; X64-BMI2-LABEL: clear_lowbits64_c1_indexzext:
 ; X64-BMI2:       # %bb.0:
 ; X64-BMI2-NEXT:    # kill: def $esi killed $esi def $rsi
-; X64-BMI2-NEXT:    movq $-1, %rax
+; X64-BMI2-NEXT:    shrxq %rsi, %rdi, %rax
 ; X64-BMI2-NEXT:    shlxq %rsi, %rax, %rax
-; X64-BMI2-NEXT:    andq %rdi, %rax
 ; X64-BMI2-NEXT:    retq
   %sh_prom = zext i8 %numlowbits to i64
   %mask = shl i64 -1, %sh_prom
@@ -640,17 +643,17 @@ define i64 @clear_lowbits64_c2_load(i64* %w, i64 %numlowbits) nounwind {
 ;
 ; X64-NOBMI2-LABEL: clear_lowbits64_c2_load:
 ; X64-NOBMI2:       # %bb.0:
-; X64-NOBMI2-NEXT:    movq $-1, %rax
-; X64-NOBMI2-NEXT:    movl %esi, %ecx
+; X64-NOBMI2-NEXT:    movq %rsi, %rcx
+; X64-NOBMI2-NEXT:    movq (%rdi), %rax
+; X64-NOBMI2-NEXT:    shrq %cl, %rax
+; X64-NOBMI2-NEXT:    # kill: def $cl killed $cl killed $rcx
 ; X64-NOBMI2-NEXT:    shlq %cl, %rax
-; X64-NOBMI2-NEXT:    andq (%rdi), %rax
 ; X64-NOBMI2-NEXT:    retq
 ;
 ; X64-BMI2-LABEL: clear_lowbits64_c2_load:
 ; X64-BMI2:       # %bb.0:
-; X64-BMI2-NEXT:    movq $-1, %rax
+; X64-BMI2-NEXT:    shrxq %rsi, (%rdi), %rax
 ; X64-BMI2-NEXT:    shlxq %rsi, %rax, %rax
-; X64-BMI2-NEXT:    andq (%rdi), %rax
 ; X64-BMI2-NEXT:    retq
   %val = load i64, i64* %w
   %mask = shl i64 -1, %numlowbits
@@ -700,18 +703,18 @@ define i64 @clear_lowbits64_c3_load_indexzext(i64* %w, i8 %numlowbits) nounwind
 ;
 ; X64-NOBMI2-LABEL: clear_lowbits64_c3_load_indexzext:
 ; X64-NOBMI2:       # %bb.0:
-; X64-NOBMI2-NEXT:    movq $-1, %rax
 ; X64-NOBMI2-NEXT:    movl %esi, %ecx
+; X64-NOBMI2-NEXT:    movq (%rdi), %rax
+; X64-NOBMI2-NEXT:    shrq %cl, %rax
+; X64-NOBMI2-NEXT:    # kill: def $cl killed $cl killed $ecx
 ; X64-NOBMI2-NEXT:    shlq %cl, %rax
-; X64-NOBMI2-NEXT:    andq (%rdi), %rax
 ; X64-NOBMI2-NEXT:    retq
 ;
 ; X64-BMI2-LABEL: clear_lowbits64_c3_load_indexzext:
 ; X64-BMI2:       # %bb.0:
 ; X64-BMI2-NEXT:    # kill: def $esi killed $esi def $rsi
-; X64-BMI2-NEXT:    movq $-1, %rax
+; X64-BMI2-NEXT:    shrxq %rsi, (%rdi), %rax
 ; X64-BMI2-NEXT:    shlxq %rsi, %rax, %rax
-; X64-BMI2-NEXT:    andq (%rdi), %rax
 ; X64-BMI2-NEXT:    retq
   %val = load i64, i64* %w
   %sh_prom = zext i8 %numlowbits to i64
@@ -756,17 +759,17 @@ define i64 @clear_lowbits64_c4_commutative(i64 %val, i64 %numlowbits) nounwind {
 ;
 ; X64-NOBMI2-LABEL: clear_lowbits64_c4_commutative:
 ; X64-NOBMI2:       # %bb.0:
-; X64-NOBMI2-NEXT:    movq $-1, %rax
-; X64-NOBMI2-NEXT:    movl %esi, %ecx
-; X64-NOBMI2-NEXT:    shlq %cl, %rax
-; X64-NOBMI2-NEXT:    andq %rdi, %rax
+; X64-NOBMI2-NEXT:    movq %rsi, %rcx
+; X64-NOBMI2-NEXT:    shrq %cl, %rdi
+; X64-NOBMI2-NEXT:    # kill: def $cl killed $cl killed $rcx
+; X64-NOBMI2-NEXT:    shlq %cl, %rdi
+; X64-NOBMI2-NEXT:    movq %rdi, %rax
 ; X64-NOBMI2-NEXT:    retq
 ;
 ; X64-BMI2-LABEL: clear_lowbits64_c4_commutative:
 ; X64-BMI2:       # %bb.0:
-; X64-BMI2-NEXT:    movq $-1, %rax
+; X64-BMI2-NEXT:    shrxq %rsi, %rdi, %rax
 ; X64-BMI2-NEXT:    shlxq %rsi, %rax, %rax
-; X64-BMI2-NEXT:    andq %rdi, %rax
 ; X64-BMI2-NEXT:    retq
   %mask = shl i64 -1, %numlowbits
   %masked = and i64 %val, %mask ; swapped order
@@ -782,20 +785,20 @@ define i64 @clear_lowbits64_c4_commutative(i64 %val, i64 %numlowbits) nounwind {
 define i8 @clear_lowbits8_ic0(i8 %val, i8 %numlowbits) nounwind {
 ; X86-LABEL: clear_lowbits8_ic0:
 ; X86:       # %bb.0:
+; X86-NEXT:    movb {{[0-9]+}}(%esp), %al
 ; X86-NEXT:    movb $8, %cl
 ; X86-NEXT:    subb {{[0-9]+}}(%esp), %cl
-; X86-NEXT:    movb $-1, %al
+; X86-NEXT:    shrb %cl, %al
 ; X86-NEXT:    shlb %cl, %al
-; X86-NEXT:    andb {{[0-9]+}}(%esp), %al
 ; X86-NEXT:    retl
 ;
 ; X64-LABEL: clear_lowbits8_ic0:
 ; X64:       # %bb.0:
 ; X64-NEXT:    movb $8, %cl
 ; X64-NEXT:    subb %sil, %cl
-; X64-NEXT:    movb $-1, %al
-; X64-NEXT:    shlb %cl, %al
-; X64-NEXT:    andb %dil, %al
+; X64-NEXT:    shrb %cl, %dil
+; X64-NEXT:    shlb %cl, %dil
+; X64-NEXT:    movl %edi, %eax
 ; X64-NEXT:    retq
   %numhighbits = sub i8 8, %numlowbits
   %mask = shl i8 -1, %numhighbits
@@ -806,21 +809,21 @@ define i8 @clear_lowbits8_ic0(i8 %val, i8 %numlowbits) nounwind {
 define i8 @clear_lowbits8_ic2_load(i8* %w, i8 %numlowbits) nounwind {
 ; X86-LABEL: clear_lowbits8_ic2_load:
 ; X86:       # %bb.0:
-; X86-NEXT:    movl {{[0-9]+}}(%esp), %edx
+; X86-NEXT:    movl {{[0-9]+}}(%esp), %eax
+; X86-NEXT:    movb (%eax), %al
 ; X86-NEXT:    movb $8, %cl
 ; X86-NEXT:    subb {{[0-9]+}}(%esp), %cl
-; X86-NEXT:    movb $-1, %al
+; X86-NEXT:    shrb %cl, %al
 ; X86-NEXT:    shlb %cl, %al
-; X86-NEXT:    andb (%edx), %al
 ; X86-NEXT:    retl
 ;
 ; X64-LABEL: clear_lowbits8_ic2_load:
 ; X64:       # %bb.0:
+; X64-NEXT:    movb (%rdi), %al
 ; X64-NEXT:    movb $8, %cl
 ; X64-NEXT:    subb %sil, %cl
-; X64-NEXT:    movb $-1, %al
+; X64-NEXT:    shrb %cl, %al
 ; X64-NEXT:    shlb %cl, %al
-; X64-NEXT:    andb (%rdi), %al
 ; X64-NEXT:    retq
   %val = load i8, i8* %w
   %numhighbits = sub i8 8, %numlowbits
@@ -832,20 +835,20 @@ define i8 @clear_lowbits8_ic2_load(i8* %w, i8 %numlowbits) nounwind {
 define i8 @clear_lowbits8_ic4_commutative(i8 %val, i8 %numlowbits) nounwind {
 ; X86-LABEL: clear_lowbits8_ic4_commutative:
 ; X86:       # %bb.0:
+; X86-NEXT:    movb {{[0-9]+}}(%esp), %al
 ; X86-NEXT:    movb $8, %cl
 ; X86-NEXT:    subb {{[0-9]+}}(%esp), %cl
-; X86-NEXT:    movb $-1, %al
+; X86-NEXT:    shrb %cl, %al
 ; X86-NEXT:    shlb %cl, %al
-; X86-NEXT:    andb {{[0-9]+}}(%esp), %al
 ; X86-NEXT:    retl
 ;
 ; X64-LABEL: clear_lowbits8_ic4_commutative:
 ; X64:       # %bb.0:
 ; X64-NEXT:    movb $8, %cl
 ; X64-NEXT:    subb %sil, %cl
-; X64-NEXT:    movb $-1, %al
-; X64-NEXT:    shlb %cl, %al
-; X64-NEXT:    andb %dil, %al
+; X64-NEXT:    shrb %cl, %dil
+; X64-NEXT:    shlb %cl, %dil
+; X64-NEXT:    movl %edi, %eax
 ; X64-NEXT:    retq
   %numhighbits = sub i8 8, %numlowbits
   %mask = shl i8 -1, %numhighbits
@@ -858,43 +861,43 @@ define i8 @clear_lowbits8_ic4_commutative(i8 %val, i8 %numlowbits) nounwind {
 define i16 @clear_lowbits16_ic0(i16 %val, i16 %numlowbits) nounwind {
 ; X86-NOBMI2-LABEL: clear_lowbits16_ic0:
 ; X86-NOBMI2:       # %bb.0:
+; X86-NOBMI2-NEXT:    movzwl {{[0-9]+}}(%esp), %eax
 ; X86-NOBMI2-NEXT:    movw $16, %cx
 ; X86-NOBMI2-NEXT:    subw {{[0-9]+}}(%esp), %cx
-; X86-NOBMI2-NEXT:    movl $-1, %eax
+; X86-NOBMI2-NEXT:    shrl %cl, %eax
 ; X86-NOBMI2-NEXT:    # kill: def $cl killed $cl killed $cx
 ; X86-NOBMI2-NEXT:    shll %cl, %eax
-; X86-NOBMI2-NEXT:    andw {{[0-9]+}}(%esp), %ax
 ; X86-NOBMI2-NEXT:    # kill: def $ax killed $ax killed $eax
 ; X86-NOBMI2-NEXT:    retl
 ;
 ; X86-BMI2-LABEL: clear_lowbits16_ic0:
 ; X86-BMI2:       # %bb.0:
-; X86-BMI2-NEXT:    movw $16, %ax
-; X86-BMI2-NEXT:    subw {{[0-9]+}}(%esp), %ax
-; X86-BMI2-NEXT:    movl $-1, %ecx
-; X86-BMI2-NEXT:    shlxl %eax, %ecx, %eax
-; X86-BMI2-NEXT:    andw {{[0-9]+}}(%esp), %ax
+; X86-BMI2-NEXT:    movzwl {{[0-9]+}}(%esp), %eax
+; X86-BMI2-NEXT:    movw $16, %cx
+; X86-BMI2-NEXT:    subw {{[0-9]+}}(%esp), %cx
+; X86-BMI2-NEXT:    shrxl %ecx, %eax, %eax
+; X86-BMI2-NEXT:    shlxl %ecx, %eax, %eax
 ; X86-BMI2-NEXT:    # kill: def $ax killed $ax killed $eax
 ; X86-BMI2-NEXT:    retl
 ;
 ; X64-NOBMI2-LABEL: clear_lowbits16_ic0:
 ; X64-NOBMI2:       # %bb.0:
+; X64-NOBMI2-NEXT:    movzwl %di, %eax
 ; X64-NOBMI2-NEXT:    movl $16, %ecx
 ; X64-NOBMI2-NEXT:    subl %esi, %ecx
-; X64-NOBMI2-NEXT:    movl $-1, %eax
+; X64-NOBMI2-NEXT:    shrl %cl, %eax
 ; X64-NOBMI2-NEXT:    # kill: def $cl killed $cl killed $ecx
 ; X64-NOBMI2-NEXT:    shll %cl, %eax
-; X64-NOBMI2-NEXT:    andl %edi, %eax
 ; X64-NOBMI2-NEXT:    # kill: def $ax killed $ax killed $eax
 ; X64-NOBMI2-NEXT:    retq
 ;
 ; X64-BMI2-LABEL: clear_lowbits16_ic0:
 ; X64-BMI2:       # %bb.0:
-; X64-BMI2-NEXT:    movl $16, %eax
-; X64-BMI2-NEXT:    subl %esi, %eax
-; X64-BMI2-NEXT:    movl $-1, %ecx
-; X64-BMI2-NEXT:    shlxl %eax, %ecx, %eax
-; X64-BMI2-NEXT:    andl %edi, %eax
+; X64-BMI2-NEXT:    movzwl %di, %eax
+; X64-BMI2-NEXT:    movl $16, %ecx
+; X64-BMI2-NEXT:    subl %esi, %ecx
+; X64-BMI2-NEXT:    shrxl %ecx, %eax, %eax
+; X64-BMI2-NEXT:    shlxl %ecx, %eax, %eax
 ; X64-BMI2-NEXT:    # kill: def $ax killed $ax killed $eax
 ; X64-BMI2-NEXT:    retq
   %numhighbits = sub i16 16, %numlowbits
@@ -906,41 +909,41 @@ define i16 @clear_lowbits16_ic0(i16 %val, i16 %numlowbits) nounwind {
 define i16 @clear_lowbits16_ic1_indexzext(i16 %val, i8 %numlowbits) nounwind {
 ; X86-NOBMI2-LABEL: clear_lowbits16_ic1_indexzext:
 ; X86-NOBMI2:       # %bb.0:
+; X86-NOBMI2-NEXT:    movzwl {{[0-9]+}}(%esp), %eax
 ; X86-NOBMI2-NEXT:    movb $16, %cl
 ; X86-NOBMI2-NEXT:    subb {{[0-9]+}}(%esp), %cl
-; X86-NOBMI2-NEXT:    movl $-1, %eax
+; X86-NOBMI2-NEXT:    shrl %cl, %eax
 ; X86-NOBMI2-NEXT:    shll %cl, %eax
-; X86-NOBMI2-NEXT:    andw {{[0-9]+}}(%esp), %ax
 ; X86-NOBMI2-NEXT:    # kill: def $ax killed $ax killed $eax
 ; X86-NOBMI2-NEXT:    retl
 ;
 ; X86-BMI2-LABEL: clear_lowbits16_ic1_indexzext:
 ; X86-BMI2:       # %bb.0:
-; X86-BMI2-NEXT:    movb $16, %al
-; X86-BMI2-NEXT:    subb {{[0-9]+}}(%esp), %al
-; X86-BMI2-NEXT:    movl $-1, %ecx
-; X86-BMI2-NEXT:    shlxl %eax, %ecx, %eax
-; X86-BMI2-NEXT:    andw {{[0-9]+}}(%esp), %ax
+; X86-BMI2-NEXT:    movzwl {{[0-9]+}}(%esp), %eax
+; X86-BMI2-NEXT:    movb $16, %cl
+; X86-BMI2-NEXT:    subb {{[0-9]+}}(%esp), %cl
+; X86-BMI2-NEXT:    shrxl %ecx, %eax, %eax
+; X86-BMI2-NEXT:    shlxl %ecx, %eax, %eax
 ; X86-BMI2-NEXT:    # kill: def $ax killed $ax killed $eax
 ; X86-BMI2-NEXT:    retl
 ;
 ; X64-NOBMI2-LABEL: clear_lowbits16_ic1_indexzext:
 ; X64-NOBMI2:       # %bb.0:
+; X64-NOBMI2-NEXT:    movzwl %di, %eax
 ; X64-NOBMI2-NEXT:    movb $16, %cl
 ; X64-NOBMI2-NEXT:    subb %sil, %cl
-; X64-NOBMI2-NEXT:    movl $-1, %eax
+; X64-NOBMI2-NEXT:    shrl %cl, %eax
 ; X64-NOBMI2-NEXT:    shll %cl, %eax
-; X64-NOBMI2-NEXT:    andl %edi, %eax
 ; X64-NOBMI2-NEXT:    # kill: def $ax killed $ax killed $eax
 ; X64-NOBMI2-NEXT:    retq
 ;
 ; X64-BMI2-LABEL: clear_lowbits16_ic1_indexzext:
 ; X64-BMI2:       # %bb.0:
-; X64-BMI2-NEXT:    movb $16, %al
-; X64-BMI2-NEXT:    subb %sil, %al
-; X64-BMI2-NEXT:    movl $-1, %ecx
-; X64-BMI2-NEXT:    shlxl %eax, %ecx, %eax
-; X64-BMI2-NEXT:    andl %edi, %eax
+; X64-BMI2-NEXT:    movzwl %di, %eax
+; X64-BMI2-NEXT:    movb $16, %cl
+; X64-BMI2-NEXT:    subb %sil, %cl
+; X64-BMI2-NEXT:    shrxl %ecx, %eax, %eax
+; X64-BMI2-NEXT:    shlxl %ecx, %eax, %eax
 ; X64-BMI2-NEXT:    # kill: def $ax killed $ax killed $eax
 ; X64-BMI2-NEXT:    retq
   %numhighbits = sub i8 16, %numlowbits
@@ -953,45 +956,45 @@ define i16 @clear_lowbits16_ic1_indexzext(i16 %val, i8 %numlowbits) nounwind {
 define i16 @clear_lowbits16_ic2_load(i16* %w, i16 %numlowbits) nounwind {
 ; X86-NOBMI2-LABEL: clear_lowbits16_ic2_load:
 ; X86-NOBMI2:       # %bb.0:
-; X86-NOBMI2-NEXT:    movl {{[0-9]+}}(%esp), %edx
+; X86-NOBMI2-NEXT:    movl {{[0-9]+}}(%esp), %eax
+; X86-NOBMI2-NEXT:    movzwl (%eax), %eax
 ; X86-NOBMI2-NEXT:    movw $16, %cx
 ; X86-NOBMI2-NEXT:    subw {{[0-9]+}}(%esp), %cx
-; X86-NOBMI2-NEXT:    movl $-1, %eax
+; X86-NOBMI2-NEXT:    shrl %cl, %eax
 ; X86-NOBMI2-NEXT:    # kill: def $cl killed $cl killed $cx
 ; X86-NOBMI2-NEXT:    shll %cl, %eax
-; X86-NOBMI2-NEXT:    andw (%edx), %ax
 ; X86-NOBMI2-NEXT:    # kill: def $ax killed $ax killed $eax
 ; X86-NOBMI2-NEXT:    retl
 ;
 ; X86-BMI2-LABEL: clear_lowbits16_ic2_load:
 ; X86-BMI2:       # %bb.0:
-; X86-BMI2-NEXT:    movl {{[0-9]+}}(%esp), %ecx
-; X86-BMI2-NEXT:    movw $16, %ax
-; X86-BMI2-NEXT:    subw {{[0-9]+}}(%esp), %ax
-; X86-BMI2-NEXT:    movl $-1, %edx
-; X86-BMI2-NEXT:    shlxl %eax, %edx, %eax
-; X86-BMI2-NEXT:    andw (%ecx), %ax
+; X86-BMI2-NEXT:    movl {{[0-9]+}}(%esp), %eax
+; X86-BMI2-NEXT:    movzwl (%eax), %eax
+; X86-BMI2-NEXT:    movw $16, %cx
+; X86-BMI2-NEXT:    subw {{[0-9]+}}(%esp), %cx
+; X86-BMI2-NEXT:    shrxl %ecx, %eax, %eax
+; X86-BMI2-NEXT:    shlxl %ecx, %eax, %eax
 ; X86-BMI2-NEXT:    # kill: def $ax killed $ax killed $eax
 ; X86-BMI2-NEXT:    retl
 ;
 ; X64-NOBMI2-LABEL: clear_lowbits16_ic2_load:
 ; X64-NOBMI2:       # %bb.0:
+; X64-NOBMI2-NEXT:    movzwl (%rdi), %eax
 ; X64-NOBMI2-NEXT:    movl $16, %ecx
 ; X64-NOBMI2-NEXT:    subl %esi, %ecx
-; X64-NOBMI2-NEXT:    movl $-1, %eax
+; X64-NOBMI2-NEXT:    shrl %cl, %eax
 ; X64-NOBMI2-NEXT:    # kill: def $cl killed $cl killed $ecx
 ; X64-NOBMI2-NEXT:    shll %cl, %eax
-; X64-NOBMI2-NEXT:    andw (%rdi), %ax
 ; X64-NOBMI2-NEXT:    # kill: def $ax killed $ax killed $eax
 ; X64-NOBMI2-NEXT:    retq
 ;
 ; X64-BMI2-LABEL: clear_lowbits16_ic2_load:
 ; X64-BMI2:       # %bb.0:
-; X64-BMI2-NEXT:    movl $16, %eax
-; X64-BMI2-NEXT:    subl %esi, %eax
-; X64-BMI2-NEXT:    movl $-1, %ecx
-; X64-BMI2-NEXT:    shlxl %eax, %ecx, %eax
-; X64-BMI2-NEXT:    andw (%rdi), %ax
+; X64-BMI2-NEXT:    movzwl (%rdi), %eax
+; X64-BMI2-NEXT:    movl $16, %ecx
+; X64-BMI2-NEXT:    subl %esi, %ecx
+; X64-BMI2-NEXT:    shrxl %ecx, %eax, %eax
+; X64-BMI2-NEXT:    shlxl %ecx, %eax, %eax
 ; X64-BMI2-NEXT:    # kill: def $ax killed $ax killed $eax
 ; X64-BMI2-NEXT:    retq
   %val = load i16, i16* %w
@@ -1004,43 +1007,43 @@ define i16 @clear_lowbits16_ic2_load(i16* %w, i16 %numlowbits) nounwind {
 define i16 @clear_lowbits16_ic3_load_indexzext(i16* %w, i8 %numlowbits) nounwind {
 ; X86-NOBMI2-LABEL: clear_lowbits16_ic3_load_indexzext:
 ; X86-NOBMI2:       # %bb.0:
-; X86-NOBMI2-NEXT:    movl {{[0-9]+}}(%esp), %edx
+; X86-NOBMI2-NEXT:    movl {{[0-9]+}}(%esp), %eax
+; X86-NOBMI2-NEXT:    movzwl (%eax), %eax
 ; X86-NOBMI2-NEXT:    movb $16, %cl
 ; X86-NOBMI2-NEXT:    subb {{[0-9]+}}(%esp), %cl
-; X86-NOBMI2-NEXT:    movl $-1, %eax
+; X86-NOBMI2-NEXT:    shrl %cl, %eax
 ; X86-NOBMI2-NEXT:    shll %cl, %eax
-; X86-NOBMI2-NEXT:    andw (%edx), %ax
 ; X86-NOBMI2-NEXT:    # kill: def $ax killed $ax killed $eax
 ; X86-NOBMI2-NEXT:    retl
 ;
 ; X86-BMI2-LABEL: clear_lowbits16_ic3_load_indexzext:
 ; X86-BMI2:       # %bb.0:
-; X86-BMI2-NEXT:    movl {{[0-9]+}}(%esp), %ecx
-; X86-BMI2-NEXT:    movb $16, %al
-; X86-BMI2-NEXT:    subb {{[0-9]+}}(%esp), %al
-; X86-BMI2-NEXT:    movl $-1, %edx
-; X86-BMI2-NEXT:    shlxl %eax, %edx, %eax
-; X86-BMI2-NEXT:    andw (%ecx), %ax
+; X86-BMI2-NEXT:    movl {{[0-9]+}}(%esp), %eax
+; X86-BMI2-NEXT:    movzwl (%eax), %eax
+; X86-BMI2-NEXT:    movb $16, %cl
+; X86-BMI2-NEXT:    subb {{[0-9]+}}(%esp), %cl
+; X86-BMI2-NEXT:    shrxl %ecx, %eax, %eax
+; X86-BMI2-NEXT:    shlxl %ecx, %eax, %eax
 ; X86-BMI2-NEXT:    # kill: def $ax killed $ax killed $eax
 ; X86-BMI2-NEXT:    retl
 ;
 ; X64-NOBMI2-LABEL: clear_lowbits16_ic3_load_indexzext:
 ; X64-NOBMI2:       # %bb.0:
+; X64-NOBMI2-NEXT:    movzwl (%rdi), %eax
 ; X64-NOBMI2-NEXT:    movb $16, %cl
 ; X64-NOBMI2-NEXT:    subb %sil, %cl
-; X64-NOBMI2-NEXT:    movl $-1, %eax
+; X64-NOBMI2-NEXT:    shrl %cl, %eax
 ; X64-NOBMI2-NEXT:    shll %cl, %eax
-; X64-NOBMI2-NEXT:    andw (%rdi), %ax
 ; X64-NOBMI2-NEXT:    # kill: def $ax killed $ax killed $eax
 ; X64-NOBMI2-NEXT:    retq
 ;
 ; X64-BMI2-LABEL: clear_lowbits16_ic3_load_indexzext:
 ; X64-BMI2:       # %bb.0:
-; X64-BMI2-NEXT:    movb $16, %al
-; X64-BMI2-NEXT:    subb %sil, %al
-; X64-BMI2-NEXT:    movl $-1, %ecx
-; X64-BMI2-NEXT:    shlxl %eax, %ecx, %eax
-; X64-BMI2-NEXT:    andw (%rdi), %ax
+; X64-BMI2-NEXT:    movzwl (%rdi), %eax
+; X64-BMI2-NEXT:    movb $16, %cl
+; X64-BMI2-NEXT:    subb %sil, %cl
+; X64-BMI2-NEXT:    shrxl %ecx, %eax, %eax
+; X64-BMI2-NEXT:    shlxl %ecx, %eax, %eax
 ; X64-BMI2-NEXT:    # kill: def $ax killed $ax killed $eax
 ; X64-BMI2-NEXT:    retq
   %val = load i16, i16* %w
@@ -1054,43 +1057,43 @@ define i16 @clear_lowbits16_ic3_load_indexzext(i16* %w, i8 %numlowbits) nounwind
 define i16 @clear_lowbits16_ic4_commutative(i16 %val, i16 %numlowbits) nounwind {
 ; X86-NOBMI2-LABEL: clear_lowbits16_ic4_commutative:
 ; X86-NOBMI2:       # %bb.0:
+; X86-NOBMI2-NEXT:    movzwl {{[0-9]+}}(%esp), %eax
 ; X86-NOBMI2-NEXT:    movw $16, %cx
 ; X86-NOBMI2-NEXT:    subw {{[0-9]+}}(%esp), %cx
-; X86-NOBMI2-NEXT:    movl $-1, %eax
+; X86-NOBMI2-NEXT:    shrl %cl, %eax
 ; X86-NOBMI2-NEXT:    # kill: def $cl killed $cl killed $cx
 ; X86-NOBMI2-NEXT:    shll %cl, %eax
-; X86-NOBMI2-NEXT:    andw {{[0-9]+}}(%esp), %ax
 ; X86-NOBMI2-NEXT:    # kill: def $ax killed $ax killed $eax
 ; X86-NOBMI2-NEXT:    retl
 ;
 ; X86-BMI2-LABEL: clear_lowbits16_ic4_commutative:
 ; X86-BMI2:       # %bb.0:
-; X86-BMI2-NEXT:    movw $16, %ax
-; X86-BMI2-NEXT:    subw {{[0-9]+}}(%esp), %ax
-; X86-BMI2-NEXT:    movl $-1, %ecx
-; X86-BMI2-NEXT:    shlxl %eax, %ecx, %eax
-; X86-BMI2-NEXT:    andw {{[0-9]+}}(%esp), %ax
+; X86-BMI2-NEXT:    movzwl {{[0-9]+}}(%esp), %eax
+; X86-BMI2-NEXT:    movw $16, %cx
+; X86-BMI2-NEXT:    subw {{[0-9]+}}(%esp), %cx
+; X86-BMI2-NEXT:    shrxl %ecx, %eax, %eax
+; X86-BMI2-NEXT:    shlxl %ecx, %eax, %eax
 ; X86-BMI2-NEXT:    # kill: def $ax killed $ax killed $eax
 ; X86-BMI2-NEXT:    retl
 ;
 ; X64-NOBMI2-LABEL: clear_lowbits16_ic4_commutative:
 ; X64-NOBMI2:       # %bb.0:
+; X64-NOBMI2-NEXT:    movzwl %di, %eax
 ; X64-NOBMI2-NEXT:    movl $16, %ecx
 ; X64-NOBMI2-NEXT:    subl %esi, %ecx
-; X64-NOBMI2-NEXT:    movl $-1, %eax
+; X64-NOBMI2-NEXT:    shrl %cl, %eax
 ; X64-NOBMI2-NEXT:    # kill: def $cl killed $cl killed $ecx
 ; X64-NOBMI2-NEXT:    shll %cl, %eax
-; X64-NOBMI2-NEXT:    andl %edi, %eax
 ; X64-NOBMI2-NEXT:    # kill: def $ax killed $ax killed $eax
 ; X64-NOBMI2-NEXT:    retq
 ;
 ; X64-BMI2-LABEL: clear_lowbits16_ic4_commutative:
 ; X64-BMI2:       # %bb.0:
-; X64-BMI2-NEXT:    movl $16, %eax
-; X64-BMI2-NEXT:    subl %esi, %eax
-; X64-BMI2-NEXT:    movl $-1, %ecx
-; X64-BMI2-NEXT:    shlxl %eax, %ecx, %eax
-; X64-BMI2-NEXT:    andl %edi, %eax
+; X64-BMI2-NEXT:    movzwl %di, %eax
+; X64-BMI2-NEXT:    movl $16, %ecx
+; X64-BMI2-NEXT:    subl %esi, %ecx
+; X64-BMI2-NEXT:    shrxl %ecx, %eax, %eax
+; X64-BMI2-NEXT:    shlxl %ecx, %eax, %eax
 ; X64-BMI2-NEXT:    # kill: def $ax killed $ax killed $eax
 ; X64-BMI2-NEXT:    retq
   %numhighbits = sub i16 16, %numlowbits
@@ -1104,40 +1107,38 @@ define i16 @clear_lowbits16_ic4_commutative(i16 %val, i16 %numlowbits) nounwind
 define i32 @clear_lowbits32_ic0(i32 %val, i32 %numlowbits) nounwind {
 ; X86-NOBMI2-LABEL: clear_lowbits32_ic0:
 ; X86-NOBMI2:       # %bb.0:
+; X86-NOBMI2-NEXT:    movl {{[0-9]+}}(%esp), %eax
 ; X86-NOBMI2-NEXT:    movl $32, %ecx
 ; X86-NOBMI2-NEXT:    subl {{[0-9]+}}(%esp), %ecx
-; X86-NOBMI2-NEXT:    movl $-1, %eax
+; X86-NOBMI2-NEXT:    shrl %cl, %eax
 ; X86-NOBMI2-NEXT:    # kill: def $cl killed $cl killed $ecx
 ; X86-NOBMI2-NEXT:    shll %cl, %eax
-; X86-NOBMI2-NEXT:    andl {{[0-9]+}}(%esp), %eax
 ; X86-NOBMI2-NEXT:    retl
 ;
 ; X86-BMI2-LABEL: clear_lowbits32_ic0:
 ; X86-BMI2:       # %bb.0:
 ; X86-BMI2-NEXT:    movl $32, %eax
 ; X86-BMI2-NEXT:    subl {{[0-9]+}}(%esp), %eax
-; X86-BMI2-NEXT:    movl $-1, %ecx
+; X86-BMI2-NEXT:    shrxl %eax, {{[0-9]+}}(%esp), %ecx
 ; X86-BMI2-NEXT:    shlxl %eax, %ecx, %eax
-; X86-BMI2-NEXT:    andl {{[0-9]+}}(%esp), %eax
 ; X86-BMI2-NEXT:    retl
 ;
 ; X64-NOBMI2-LABEL: clear_lowbits32_ic0:
 ; X64-NOBMI2:       # %bb.0:
 ; X64-NOBMI2-NEXT:    movl $32, %ecx
 ; X64-NOBMI2-NEXT:    subl %esi, %ecx
-; X64-NOBMI2-NEXT:    movl $-1, %eax
+; X64-NOBMI2-NEXT:    shrl %cl, %edi
 ; X64-NOBMI2-NEXT:    # kill: def $cl killed $cl killed $ecx
-; X64-NOBMI2-NEXT:    shll %cl, %eax
-; X64-NOBMI2-NEXT:    andl %edi, %eax
+; X64-NOBMI2-NEXT:    shll %cl, %edi
+; X64-NOBMI2-NEXT:    movl %edi, %eax
 ; X64-NOBMI2-NEXT:    retq
 ;
 ; X64-BMI2-LABEL: clear_lowbits32_ic0:
 ; X64-BMI2:       # %bb.0:
 ; X64-BMI2-NEXT:    movl $32, %eax
 ; X64-BMI2-NEXT:    subl %esi, %eax
-; X64-BMI2-NEXT:    movl $-1, %ecx
+; X64-BMI2-NEXT:    shrxl %eax, %edi, %ecx
 ; X64-BMI2-NEXT:    shlxl %eax, %ecx, %eax
-; X64-BMI2-NEXT:    andl %edi, %eax
 ; X64-BMI2-NEXT:    retq
   %numhighbits = sub i32 32, %numlowbits
   %mask = shl i32 -1, %numhighbits
@@ -1148,38 +1149,36 @@ define i32 @clear_lowbits32_ic0(i32 %val, i32 %numlowbits) nounwind {
 define i32 @clear_lowbits32_ic1_indexzext(i32 %val, i8 %numlowbits) nounwind {
 ; X86-NOBMI2-LABEL: clear_lowbits32_ic1_indexzext:
 ; X86-NOBMI2:       # %bb.0:
+; X86-NOBMI2-NEXT:    movl {{[0-9]+}}(%esp), %eax
 ; X86-NOBMI2-NEXT:    movb $32, %cl
 ; X86-NOBMI2-NEXT:    subb {{[0-9]+}}(%esp), %cl
-; X86-NOBMI2-NEXT:    movl $-1, %eax
+; X86-NOBMI2-NEXT:    shrl %cl, %eax
 ; X86-NOBMI2-NEXT:    shll %cl, %eax
-; X86-NOBMI2-NEXT:    andl {{[0-9]+}}(%esp), %eax
 ; X86-NOBMI2-NEXT:    retl
 ;
 ; X86-BMI2-LABEL: clear_lowbits32_ic1_indexzext:
 ; X86-BMI2:       # %bb.0:
 ; X86-BMI2-NEXT:    movb $32, %al
 ; X86-BMI2-NEXT:    subb {{[0-9]+}}(%esp), %al
-; X86-BMI2-NEXT:    movl $-1, %ecx
+; X86-BMI2-NEXT:    shrxl %eax, {{[0-9]+}}(%esp), %ecx
 ; X86-BMI2-NEXT:    shlxl %eax, %ecx, %eax
-; X86-BMI2-NEXT:    andl {{[0-9]+}}(%esp), %eax
 ; X86-BMI2-NEXT:    retl
 ;
 ; X64-NOBMI2-LABEL: clear_lowbits32_ic1_indexzext:
 ; X64-NOBMI2:       # %bb.0:
 ; X64-NOBMI2-NEXT:    movb $32, %cl
 ; X64-NOBMI2-NEXT:    subb %sil, %cl
-; X64-NOBMI2-NEXT:    movl $-1, %eax
-; X64-NOBMI2-NEXT:    shll %cl, %eax
-; X64-NOBMI2-NEXT:    andl %edi, %eax
+; X64-NOBMI2-NEXT:    shrl %cl, %edi
+; X64-NOBMI2-NEXT:    shll %cl, %edi
+; X64-NOBMI2-NEXT:    movl %edi, %eax
 ; X64-NOBMI2-NEXT:    retq
 ;
 ; X64-BMI2-LABEL: clear_lowbits32_ic1_indexzext:
 ; X64-BMI2:       # %bb.0:
 ; X64-BMI2-NEXT:    movb $32, %al
 ; X64-BMI2-NEXT:    subb %sil, %al
-; X64-BMI2-NEXT:    movl $-1, %ecx
+; X64-BMI2-NEXT:    shrxl %eax, %edi, %ecx
 ; X64-BMI2-NEXT:    shlxl %eax, %ecx, %eax
-; X64-BMI2-NEXT:    andl %edi, %eax
 ; X64-BMI2-NEXT:    retq
   %numhighbits = sub i8 32, %numlowbits
   %sh_prom = zext i8 %numhighbits to i32
@@ -1191,42 +1190,40 @@ define i32 @clear_lowbits32_ic1_indexzext(i32 %val, i8 %numlowbits) nounwind {
 define i32 @clear_lowbits32_ic2_load(i32* %w, i32 %numlowbits) nounwind {
 ; X86-NOBMI2-LABEL: clear_lowbits32_ic2_load:
 ; X86-NOBMI2:       # %bb.0:
-; X86-NOBMI2-NEXT:    movl {{[0-9]+}}(%esp), %edx
+; X86-NOBMI2-NEXT:    movl {{[0-9]+}}(%esp), %eax
+; X86-NOBMI2-NEXT:    movl (%eax), %eax
 ; X86-NOBMI2-NEXT:    movl $32, %ecx
 ; X86-NOBMI2-NEXT:    subl {{[0-9]+}}(%esp), %ecx
-; X86-NOBMI2-NEXT:    movl $-1, %eax
+; X86-NOBMI2-NEXT:    shrl %cl, %eax
 ; X86-NOBMI2-NEXT:    # kill: def $cl killed $cl killed $ecx
 ; X86-NOBMI2-NEXT:    shll %cl, %eax
-; X86-NOBMI2-NEXT:    andl (%edx), %eax
 ; X86-NOBMI2-NEXT:    retl
 ;
 ; X86-BMI2-LABEL: clear_lowbits32_ic2_load:
 ; X86-BMI2:       # %bb.0:
-; X86-BMI2-NEXT:    movl {{[0-9]+}}(%esp), %ecx
-; X86-BMI2-NEXT:    movl $32, %eax
-; X86-BMI2-NEXT:    subl {{[0-9]+}}(%esp), %eax
-; X86-BMI2-NEXT:    movl $-1, %edx
-; X86-BMI2-NEXT:    shlxl %eax, %edx, %eax
-; X86-BMI2-NEXT:    andl (%ecx), %eax
+; X86-BMI2-NEXT:    movl {{[0-9]+}}(%esp), %eax
+; X86-BMI2-NEXT:    movl $32, %ecx
+; X86-BMI2-NEXT:    subl {{[0-9]+}}(%esp), %ecx
+; X86-BMI2-NEXT:    shrxl %ecx, (%eax), %eax
+; X86-BMI2-NEXT:    shlxl %ecx, %eax, %eax
 ; X86-BMI2-NEXT:    retl
 ;
 ; X64-NOBMI2-LABEL: clear_lowbits32_ic2_load:
 ; X64-NOBMI2:       # %bb.0:
+; X64-NOBMI2-NEXT:    movl (%rdi), %eax
 ; X64-NOBMI2-NEXT:    movl $32, %ecx
 ; X64-NOBMI2-NEXT:    subl %esi, %ecx
-; X64-NOBMI2-NEXT:    movl $-1, %eax
+; X64-NOBMI2-NEXT:    shrl %cl, %eax
 ; X64-NOBMI2-NEXT:    # kill: def $cl killed $cl killed $ecx
 ; X64-NOBMI2-NEXT:    shll %cl, %eax
-; X64-NOBMI2-NEXT:    andl (%rdi), %eax
 ; X64-NOBMI2-NEXT:    retq
 ;
 ; X64-BMI2-LABEL: clear_lowbits32_ic2_load:
 ; X64-BMI2:       # %bb.0:
 ; X64-BMI2-NEXT:    movl $32, %eax
 ; X64-BMI2-NEXT:    subl %esi, %eax
-; X64-BMI2-NEXT:    movl $-1, %ecx
+; X64-BMI2-NEXT:    shrxl %eax, (%rdi), %ecx
 ; X64-BMI2-NEXT:    shlxl %eax, %ecx, %eax
-; X64-BMI2-NEXT:    andl (%rdi), %eax
 ; X64-BMI2-NEXT:    retq
   %val = load i32, i32* %w
   %numhighbits = sub i32 32, %numlowbits
@@ -1238,40 +1235,38 @@ define i32 @clear_lowbits32_ic2_load(i32* %w, i32 %numlowbits) nounwind {
 define i32 @clear_lowbits32_ic3_load_indexzext(i32* %w, i8 %numlowbits) nounwind {
 ; X86-NOBMI2-LABEL: clear_lowbits32_ic3_load_indexzext:
 ; X86-NOBMI2:       # %bb.0:
-; X86-NOBMI2-NEXT:    movl {{[0-9]+}}(%esp), %edx
+; X86-NOBMI2-NEXT:    movl {{[0-9]+}}(%esp), %eax
+; X86-NOBMI2-NEXT:    movl (%eax), %eax
 ; X86-NOBMI2-NEXT:    movb $32, %cl
 ; X86-NOBMI2-NEXT:    subb {{[0-9]+}}(%esp), %cl
-; X86-NOBMI2-NEXT:    movl $-1, %eax
+; X86-NOBMI2-NEXT:    shrl %cl, %eax
 ; X86-NOBMI2-NEXT:    shll %cl, %eax
-; X86-NOBMI2-NEXT:    andl (%edx), %eax
 ; X86-NOBMI2-NEXT:    retl
 ;
 ; X86-BMI2-LABEL: clear_lowbits32_ic3_load_indexzext:
 ; X86-BMI2:       # %bb.0:
-; X86-BMI2-NEXT:    movl {{[0-9]+}}(%esp), %ecx
-; X86-BMI2-NEXT:    movb $32, %al
-; X86-BMI2-NEXT:    subb {{[0-9]+}}(%esp), %al
-; X86-BMI2-NEXT:    movl $-1, %edx
-; X86-BMI2-NEXT:    shlxl %eax, %edx, %eax
-; X86-BMI2-NEXT:    andl (%ecx), %eax
+; X86-BMI2-NEXT:    movl {{[0-9]+}}(%esp), %eax
+; X86-BMI2-NEXT:    movb $32, %cl
+; X86-BMI2-NEXT:    subb {{[0-9]+}}(%esp), %cl
+; X86-BMI2-NEXT:    shrxl %ecx, (%eax), %eax
+; X86-BMI2-NEXT:    shlxl %ecx, %eax, %eax
 ; X86-BMI2-NEXT:    retl
 ;
 ; X64-NOBMI2-LABEL: clear_lowbits32_ic3_load_indexzext:
 ; X64-NOBMI2:       # %bb.0:
+; X64-NOBMI2-NEXT:    movl (%rdi), %eax
 ; X64-NOBMI2-NEXT:    movb $32, %cl
 ; X64-NOBMI2-NEXT:    subb %sil, %cl
-; X64-NOBMI2-NEXT:    movl $-1, %eax
+; X64-NOBMI2-NEXT:    shrl %cl, %eax
 ; X64-NOBMI2-NEXT:    shll %cl, %eax
-; X64-NOBMI2-NEXT:    andl (%rdi), %eax
 ; X64-NOBMI2-NEXT:    retq
 ;
 ; X64-BMI2-LABEL: clear_lowbits32_ic3_load_indexzext:
 ; X64-BMI2:       # %bb.0:
 ; X64-BMI2-NEXT:    movb $32, %al
 ; X64-BMI2-NEXT:    subb %sil, %al
-; X64-BMI2-NEXT:    movl $-1, %ecx
+; X64-BMI2-NEXT:    shrxl %eax, (%rdi), %ecx
 ; X64-BMI2-NEXT:    shlxl %eax, %ecx, %eax
-; X64-BMI2-NEXT:    andl (%rdi), %eax
 ; X64-BMI2-NEXT:    retq
   %val = load i32, i32* %w
   %numhighbits = sub i8 32, %numlowbits
@@ -1284,40 +1279,38 @@ define i32 @clear_lowbits32_ic3_load_indexzext(i32* %w, i8 %numlowbits) nounwind
 define i32 @clear_lowbits32_ic4_commutative(i32 %val, i32 %numlowbits) nounwind {
 ; X86-NOBMI2-LABEL: clear_lowbits32_ic4_commutative:
 ; X86-NOBMI2:       # %bb.0:
+; X86-NOBMI2-NEXT:    movl {{[0-9]+}}(%esp), %eax
 ; X86-NOBMI2-NEXT:    movl $32, %ecx
 ; X86-NOBMI2-NEXT:    subl {{[0-9]+}}(%esp), %ecx
-; X86-NOBMI2-NEXT:    movl $-1, %eax
+; X86-NOBMI2-NEXT:    shrl %cl, %eax
 ; X86-NOBMI2-NEXT:    # kill: def $cl killed $cl killed $ecx
 ; X86-NOBMI2-NEXT:    shll %cl, %eax
-; X86-NOBMI2-NEXT:    andl {{[0-9]+}}(%esp), %eax
 ; X86-NOBMI2-NEXT:    retl
 ;
 ; X86-BMI2-LABEL: clear_lowbits32_ic4_commutative:
 ; X86-BMI2:       # %bb.0:
 ; X86-BMI2-NEXT:    movl $32, %eax
 ; X86-BMI2-NEXT:    subl {{[0-9]+}}(%esp), %eax
-; X86-BMI2-NEXT:    movl $-1, %ecx
+; X86-BMI2-NEXT:    shrxl %eax, {{[0-9]+}}(%esp), %ecx
 ; X86-BMI2-NEXT:    shlxl %eax, %ecx, %eax
-; X86-BMI2-NEXT:    andl {{[0-9]+}}(%esp), %eax
 ; X86-BMI2-NEXT:    retl
 ;
 ; X64-NOBMI2-LABEL: clear_lowbits32_ic4_commutative:
 ; X64-NOBMI2:       # %bb.0:
 ; X64-NOBMI2-NEXT:    movl $32, %ecx
 ; X64-NOBMI2-NEXT:    subl %esi, %ecx
-; X64-NOBMI2-NEXT:    movl $-1, %eax
+; X64-NOBMI2-NEXT:    shrl %cl, %edi
 ; X64-NOBMI2-NEXT:    # kill: def $cl killed $cl killed $ecx
-; X64-NOBMI2-NEXT:    shll %cl, %eax
-; X64-NOBMI2-NEXT:    andl %edi, %eax
+; X64-NOBMI2-NEXT:    shll %cl, %edi
+; X64-NOBMI2-NEXT:    movl %edi, %eax
 ; X64-NOBMI2-NEXT:    retq
 ;
 ; X64-BMI2-LABEL: clear_lowbits32_ic4_commutative:
 ; X64-BMI2:       # %bb.0:
 ; X64-BMI2-NEXT:    movl $32, %eax
 ; X64-BMI2-NEXT:    subl %esi, %eax
-; X64-BMI2-NEXT:    movl $-1, %ecx
+; X64-BMI2-NEXT:    shrxl %eax, %edi, %ecx
 ; X64-BMI2-NEXT:    shlxl %eax, %ecx, %eax
-; X64-BMI2-NEXT:    andl %edi, %eax
 ; X64-BMI2-NEXT:    retq
   %numhighbits = sub i32 32, %numlowbits
   %mask = shl i32 -1, %numhighbits
@@ -1367,19 +1360,18 @@ define i64 @clear_lowbits64_ic0(i64 %val, i64 %numlowbits) nounwind {
 ; X64-NOBMI2:       # %bb.0:
 ; X64-NOBMI2-NEXT:    movl $64, %ecx
 ; X64-NOBMI2-NEXT:    subl %esi, %ecx
-; X64-NOBMI2-NEXT:    movq $-1, %rax
+; X64-NOBMI2-NEXT:    shrq %cl, %rdi
 ; X64-NOBMI2-NEXT:    # kill: def $cl killed $cl killed $ecx
-; X64-NOBMI2-NEXT:    shlq %cl, %rax
-; X64-NOBMI2-NEXT:    andq %rdi, %rax
+; X64-NOBMI2-NEXT:    shlq %cl, %rdi
+; X64-NOBMI2-NEXT:    movq %rdi, %rax
 ; X64-NOBMI2-NEXT:    retq
 ;
 ; X64-BMI2-LABEL: clear_lowbits64_ic0:
 ; X64-BMI2:       # %bb.0:
 ; X64-BMI2-NEXT:    movl $64, %eax
 ; X64-BMI2-NEXT:    subl %esi, %eax
-; X64-BMI2-NEXT:    movq $-1, %rcx
+; X64-BMI2-NEXT:    shrxq %rax, %rdi, %rcx
 ; X64-BMI2-NEXT:    shlxq %rax, %rcx, %rax
-; X64-BMI2-NEXT:    andq %rdi, %rax
 ; X64-BMI2-NEXT:    retq
   %numhighbits = sub i64 64, %numlowbits
   %mask = shl i64 -1, %numhighbits
@@ -1427,18 +1419,17 @@ define i64 @clear_lowbits64_ic1_indexzext(i64 %val, i8 %numlowbits) nounwind {
 ; X64-NOBMI2:       # %bb.0:
 ; X64-NOBMI2-NEXT:    movb $64, %cl
 ; X64-NOBMI2-NEXT:    subb %sil, %cl
-; X64-NOBMI2-NEXT:    movq $-1, %rax
-; X64-NOBMI2-NEXT:    shlq %cl, %rax
-; X64-NOBMI2-NEXT:    andq %rdi, %rax
+; X64-NOBMI2-NEXT:    shrq %cl, %rdi
+; X64-NOBMI2-NEXT:    shlq %cl, %rdi
+; X64-NOBMI2-NEXT:    movq %rdi, %rax
 ; X64-NOBMI2-NEXT:    retq
 ;
 ; X64-BMI2-LABEL: clear_lowbits64_ic1_indexzext:
 ; X64-BMI2:       # %bb.0:
 ; X64-BMI2-NEXT:    movb $64, %al
 ; X64-BMI2-NEXT:    subb %sil, %al
-; X64-BMI2-NEXT:    movq $-1, %rcx
+; X64-BMI2-NEXT:    shrxq %rax, %rdi, %rcx
 ; X64-BMI2-NEXT:    shlxq %rax, %rcx, %rax
-; X64-BMI2-NEXT:    andq %rdi, %rax
 ; X64-BMI2-NEXT:    retq
   %numhighbits = sub i8 64, %numlowbits
   %sh_prom = zext i8 %numhighbits to i64
@@ -1491,21 +1482,20 @@ define i64 @clear_lowbits64_ic2_load(i64* %w, i64 %numlowbits) nounwind {
 ;
 ; X64-NOBMI2-LABEL: clear_lowbits64_ic2_load:
 ; X64-NOBMI2:       # %bb.0:
+; X64-NOBMI2-NEXT:    movq (%rdi), %rax
 ; X64-NOBMI2-NEXT:    movl $64, %ecx
 ; X64-NOBMI2-NEXT:    subl %esi, %ecx
-; X64-NOBMI2-NEXT:    movq $-1, %rax
+; X64-NOBMI2-NEXT:    shrq %cl, %rax
 ; X64-NOBMI2-NEXT:    # kill: def $cl killed $cl killed $ecx
 ; X64-NOBMI2-NEXT:    shlq %cl, %rax
-; X64-NOBMI2-NEXT:    andq (%rdi), %rax
 ; X64-NOBMI2-NEXT:    retq
 ;
 ; X64-BMI2-LABEL: clear_lowbits64_ic2_load:
 ; X64-BMI2:       # %bb.0:
 ; X64-BMI2-NEXT:    movl $64, %eax
 ; X64-BMI2-NEXT:    subl %esi, %eax
-; X64-BMI2-NEXT:    movq $-1, %rcx
+; X64-BMI2-NEXT:    shrxq %rax, (%rdi), %rcx
 ; X64-BMI2-NEXT:    shlxq %rax, %rcx, %rax
-; X64-BMI2-NEXT:    andq (%rdi), %rax
 ; X64-BMI2-NEXT:    retq
   %val = load i64, i64* %w
   %numhighbits = sub i64 64, %numlowbits
@@ -1558,20 +1548,19 @@ define i64 @clear_lowbits64_ic3_load_indexzext(i64* %w, i8 %numlowbits) nounwind
 ;
 ; X64-NOBMI2-LABEL: clear_lowbits64_ic3_load_indexzext:
 ; X64-NOBMI2:       # %bb.0:
+; X64-NOBMI2-NEXT:    movq (%rdi), %rax
 ; X64-NOBMI2-NEXT:    movb $64, %cl
 ; X64-NOBMI2-NEXT:    subb %sil, %cl
-; X64-NOBMI2-NEXT:    movq $-1, %rax
+; X64-NOBMI2-NEXT:    shrq %cl, %rax
 ; X64-NOBMI2-NEXT:    shlq %cl, %rax
-; X64-NOBMI2-NEXT:    andq (%rdi), %rax
 ; X64-NOBMI2-NEXT:    retq
 ;
 ; X64-BMI2-LABEL: clear_lowbits64_ic3_load_indexzext:
 ; X64-BMI2:       # %bb.0:
 ; X64-BMI2-NEXT:    movb $64, %al
 ; X64-BMI2-NEXT:    subb %sil, %al
-; X64-BMI2-NEXT:    movq $-1, %rcx
+; X64-BMI2-NEXT:    shrxq %rax, (%rdi), %rcx
 ; X64-BMI2-NEXT:    shlxq %rax, %rcx, %rax
-; X64-BMI2-NEXT:    andq (%rdi), %rax
 ; X64-BMI2-NEXT:    retq
   %val = load i64, i64* %w
   %numhighbits = sub i8 64, %numlowbits
@@ -1621,19 +1610,18 @@ define i64 @clear_lowbits64_ic4_commutative(i64 %val, i64 %numlowbits) nounwind
 ; X64-NOBMI2:       # %bb.0:
 ; X64-NOBMI2-NEXT:    movl $64, %ecx
 ; X64-NOBMI2-NEXT:    subl %esi, %ecx
-; X64-NOBMI2-NEXT:    movq $-1, %rax
+; X64-NOBMI2-NEXT:    shrq %cl, %rdi
 ; X64-NOBMI2-NEXT:    # kill: def $cl killed $cl killed $ecx
-; X64-NOBMI2-NEXT:    shlq %cl, %rax
-; X64-NOBMI2-NEXT:    andq %rdi, %rax
+; X64-NOBMI2-NEXT:    shlq %cl, %rdi
+; X64-NOBMI2-NEXT:    movq %rdi, %rax
 ; X64-NOBMI2-NEXT:    retq
 ;
 ; X64-BMI2-LABEL: clear_lowbits64_ic4_commutative:
 ; X64-BMI2:       # %bb.0:
 ; X64-BMI2-NEXT:    movl $64, %eax
 ; X64-BMI2-NEXT:    subl %esi, %eax
-; X64-BMI2-NEXT:    movq $-1, %rcx
+; X64-BMI2-NEXT:    shrxq %rax, %rdi, %rcx
 ; X64-BMI2-NEXT:    shlxq %rax, %rcx, %rax
-; X64-BMI2-NEXT:    andq %rdi, %rax
 ; X64-BMI2-NEXT:    retq
   %numhighbits = sub i64 64, %numlowbits
   %mask = shl i64 -1, %numhighbits