[CGP] add special-cases to form unsigned add with overflow (PR40486)

There's likely a missed IR canonicalization for at least 1 of these
patterns. Otherwise, we wouldn't have needed the pattern-matching
enhancement in D57516.

Note that -- unlike usubo added with D57789 -- the TLI hook for
this transform defaults to 'on'. So if there's any perf fallout
from this, targets should look at how they're lowering the uaddo
node in SDAG and/or override that hook.

The x86 diffs suggest that there's some missing pattern-matching
for forming inc/dec.

This should fix the remaining known problems in:
https://bugs.llvm.org/show_bug.cgi?id=40486
https://bugs.llvm.org/show_bug.cgi?id=31754

llvm-svn: 354746

2 files changed, 14 insertions, 24 deletions

diff --git a/llvm/test/CodeGen/X86/codegen-prepare-uaddo.ll b/llvm/test/CodeGen/X86/codegen-prepare-uaddo.ll
index 921f0da3b8d..2c4435bbb03 100644
--- a/llvm/test/CodeGen/X86/codegen-prepare-uaddo.ll
+++ b/llvm/test/CodeGen/X86/codegen-prepare-uaddo.ll
@@ -229,12 +229,7 @@ define void @test_18446744073709551614(i64*, i64*) {
 define void @test_18446744073709551615(i64*, i64*) {
 ; CHECK-LABEL: test_18446744073709551615:
 ; CHECK:       # %bb.0:
-; CHECK-NEXT:    movq (%rdi), %rax
-; CHECK-NEXT:    leaq -1(%rax), %rcx
-; CHECK-NEXT:    movq %rcx, (%rdi)
-; CHECK-NEXT:    testq %rax, %rax
-; CHECK-NEXT:    setne %al
-; CHECK-NEXT:    addb $-1, %al
+; CHECK-NEXT:    addq $-1, (%rdi)
 ; CHECK-NEXT:    adcq $0, (%rsi)
 ; CHECK-NEXT:    retq
   %3 = load i64, i64* %0, align 8
@@ -272,10 +267,9 @@ define i1 @illegal_type(i17 %x, i17* %p) {
 define i1 @uaddo_i64_increment_alt(i64 %x, i64* %p) {
 ; CHECK-LABEL: uaddo_i64_increment_alt:
 ; CHECK:       # %bb.0:
-; CHECK-NEXT:    leaq 1(%rdi), %rax
-; CHECK-NEXT:    movq %rax, (%rsi)
-; CHECK-NEXT:    cmpq $-1, %rdi
+; CHECK-NEXT:    incq %rdi
 ; CHECK-NEXT:    sete %al
+; CHECK-NEXT:    movq %rdi, (%rsi)
 ; CHECK-NEXT:    retq
   %a = add i64 %x, 1
   store i64 %a, i64* %p
@@ -288,9 +282,8 @@ define i1 @uaddo_i64_increment_alt(i64 %x, i64* %p) {
 define i1 @uaddo_i64_increment_alt_dom(i64 %x, i64* %p) {
 ; CHECK-LABEL: uaddo_i64_increment_alt_dom:
 ; CHECK:       # %bb.0:
-; CHECK-NEXT:    cmpq $-1, %rdi
-; CHECK-NEXT:    sete %al
 ; CHECK-NEXT:    incq %rdi
+; CHECK-NEXT:    sete %al
 ; CHECK-NEXT:    movq %rdi, (%rsi)
 ; CHECK-NEXT:    retq
   %ov = icmp eq i64 %x, -1
@@ -304,10 +297,9 @@ define i1 @uaddo_i64_increment_alt_dom(i64 %x, i64* %p) {
 define i1 @uaddo_i64_decrement_alt(i64 %x, i64* %p) {
 ; CHECK-LABEL: uaddo_i64_decrement_alt:
 ; CHECK:       # %bb.0:
-; CHECK-NEXT:    leaq -1(%rdi), %rax
-; CHECK-NEXT:    movq %rax, (%rsi)
-; CHECK-NEXT:    testq %rdi, %rdi
-; CHECK-NEXT:    setne %al
+; CHECK-NEXT:    addq $-1, %rdi
+; CHECK-NEXT:    setb %al
+; CHECK-NEXT:    movq %rdi, (%rsi)
 ; CHECK-NEXT:    retq
   %a = add i64 %x, -1
   store i64 %a, i64* %p
@@ -320,9 +312,8 @@ define i1 @uaddo_i64_decrement_alt(i64 %x, i64* %p) {
 define i1 @uaddo_i64_decrement_alt_dom(i64 %x, i64* %p) {
 ; CHECK-LABEL: uaddo_i64_decrement_alt_dom:
 ; CHECK:       # %bb.0:
-; CHECK-NEXT:    testq %rdi, %rdi
-; CHECK-NEXT:    setne %al
-; CHECK-NEXT:    decq %rdi
+; CHECK-NEXT:    addq $-1, %rdi
+; CHECK-NEXT:    setb %al
 ; CHECK-NEXT:    movq %rdi, (%rsi)
 ; CHECK-NEXT:    retq
   %ov = icmp ne i64 %x, 0
diff --git a/llvm/test/CodeGen/X86/rd-mod-wr-eflags.ll b/llvm/test/CodeGen/X86/rd-mod-wr-eflags.ll
index 410d736af73..a2fc94d70fd 100644
--- a/llvm/test/CodeGen/X86/rd-mod-wr-eflags.ll
+++ b/llvm/test/CodeGen/X86/rd-mod-wr-eflags.ll
@@ -68,13 +68,12 @@ define i32 @test2() nounwind uwtable ssp {
 ; CHECK:       # %bb.0: # %entry
 ; CHECK-NEXT:    pushq %rax
 ; CHECK-NEXT:    .cfi_def_cfa_offset 16
-; CHECK-NEXT:    movq {{.*}}(%rip), %rax
-; CHECK-NEXT:    leaq -1(%rax), %rsi
+; CHECK-NEXT:    movq {{.*}}(%rip), %rsi
+; CHECK-NEXT:    xorl %eax, %eax
+; CHECK-NEXT:    addq $-1, %rsi
+; CHECK-NEXT:    setb %al
 ; CHECK-NEXT:    movq %rsi, {{.*}}(%rip)
-; CHECK-NEXT:    xorl %ecx, %ecx
-; CHECK-NEXT:    testq %rax, %rax
-; CHECK-NEXT:    setne %cl
-; CHECK-NEXT:    movl %ecx, {{.*}}(%rip)
+; CHECK-NEXT:    movl %eax, {{.*}}(%rip)
 ; CHECK-NEXT:    movl $.L.str, %edi
 ; CHECK-NEXT:    xorl %eax, %eax
 ; CHECK-NEXT:    callq printf