[x86] add tests to show missing demanded bits analysis; NFC

llvm-svn: 288515

1 files changed, 53 insertions, 0 deletions

diff --git a/llvm/test/CodeGen/X86/not-and-simplify.ll b/llvm/test/CodeGen/X86/not-and-simplify.ll
new file mode 100644
index 00000000000..23d8cdec748
--- /dev/null
+++ b/llvm/test/CodeGen/X86/not-and-simplify.ll
@@ -0,0 +1,53 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: llc < %s -mtriple=x86_64-unknown-unknown -mattr=-bmi | FileCheck %s --check-prefix=NO_BMI
+; RUN: llc < %s -mtriple=x86_64-unknown-unknown -mattr=+bmi | FileCheck %s --check-prefix=BMI
+
+; Clear high bits via shift, set them with xor (not), then mask them off.
+
+define i32 @shrink_xor_constant1(i32 %x) {
+; NO_BMI-LABEL: shrink_xor_constant1:
+; NO_BMI:       # BB#0:
+; NO_BMI-NEXT:    shrl $31, %edi
+; NO_BMI-NEXT:    notl %edi
+; NO_BMI-NEXT:    andl $1, %edi
+; NO_BMI-NEXT:    movl %edi, %eax
+; NO_BMI-NEXT:    retq
+;
+; BMI-LABEL: shrink_xor_constant1:
+; BMI:       # BB#0:
+; BMI-NEXT:    shrl $31, %edi
+; BMI-NEXT:    movl $1, %eax
+; BMI-NEXT:    andnl %eax, %edi, %eax
+; BMI-NEXT:    retq
+;
+  %sh = lshr i32 %x, 31
+  %not = xor i32 %sh, -1
+  %and = and i32 %not, 1
+  ret i32 %and
+}
+
+; Clear low bits via shift, set them with xor (not), then mask them off.
+
+define i8 @shrink_xor_constant2(i8 %x) {
+; NO_BMI-LABEL: shrink_xor_constant2:
+; NO_BMI:       # BB#0:
+; NO_BMI-NEXT:    shlb $5, %dil
+; NO_BMI-NEXT:    notb %dil
+; NO_BMI-NEXT:    andb $-32, %dil
+; NO_BMI-NEXT:    movl %edi, %eax
+; NO_BMI-NEXT:    retq
+;
+; BMI-LABEL: shrink_xor_constant3:
+; BMI:       # BB#0:
+; BMI-NEXT:    shlb $5, %dil
+; BMI-NEXT:    notb %dil
+; BMI-NEXT:    andb $-32, %dil
+; BMI-NEXT:    movl %edi, %eax
+; BMI-NEXT:    retq
+;
+  %sh = shl i8 %x, 5
+  %not = xor i8 %sh, -1
+  %and = and i8 %not, 224 ; 0xE0
+  ret i8 %and
+}
+