[x86] use BMI 'andn' for logic + compare ops

With BMI, we can use 'andn' to save an instruction when the result is only used in a compare.
This is related to one of the potential sequences to check 'isfinite' in:
https://llvm.org/bugs/show_bug.cgi?id=27164

Differential Revision: http://reviews.llvm.org/D18910

llvm-svn: 265875

1 files changed, 4 insertions, 6 deletions

diff --git a/llvm/test/CodeGen/X86/bmi.ll b/llvm/test/CodeGen/X86/bmi.ll
index c4b9951f57a..0be3e56e663 100644
--- a/llvm/test/CodeGen/X86/bmi.ll
+++ b/llvm/test/CodeGen/X86/bmi.ll
@@ -136,12 +136,11 @@ define i64 @andn64(i64 %x, i64 %y)   {
   ret i64 %tmp2
 }
 
-; FIXME: Don't choose a 'test' if an 'andn' can be used.
+; Don't choose a 'test' if an 'andn' can be used.
 define i1 @andn_cmp(i32 %x, i32 %y) {
 ; CHECK-LABEL: andn_cmp:
 ; CHECK:       # BB#0:
-; CHECK-NEXT:    notl %edi
-; CHECK-NEXT:    testl %esi, %edi
+; CHECK-NEXT:    andnl %esi, %edi, %eax
 ; CHECK-NEXT:    sete %al
 ; CHECK-NEXT:    retq
 ;
@@ -151,12 +150,11 @@ define i1 @andn_cmp(i32 %x, i32 %y) {
   ret i1 %cmp
 }
 
-; FIXME: Don't choose a 'test' if an 'andn' can be used.
+; Don't choose a 'test' if an 'andn' can be used.
 define i1 @andn_cmp_swap_ops(i64 %x, i64 %y) {
 ; CHECK-LABEL: andn_cmp_swap_ops:
 ; CHECK:       # BB#0:
-; CHECK-NEXT:    notq %rdi
-; CHECK-NEXT:    testq %rdi, %rsi
+; CHECK-NEXT:    andnq %rsi, %rdi, %rax
 ; CHECK-NEXT:    sete %al
 ; CHECK-NEXT:    retq
 ;