[DAGCombiner] add and use TLI hook to convert and-of-seteq / or-of-setne to bitwise logic+setcc (PR32401)
This is a generic combine enabled via target hook to reduce icmp logic as discussed in:
https://bugs.llvm.org/show_bug.cgi?id=32401
It's likely that other targets will want to enable this hook for scalar transforms,
and there are probably other patterns that can use bitwise logic to reduce comparisons.
Note that we are missing an IR canonicalization for these patterns, and we will probably
prefer the pair-of-compares form in IR (shorter, more likely to fold).
Differential Revision: https://reviews.llvm.org/D31483
llvm-svn: 299542
diff --git a/llvm/test/CodeGen/X86/setcc-logic.ll b/llvm/test/CodeGen/X86/setcc-logic.ll
index 8e6c149..4d1e5ba 100644
--- a/llvm/test/CodeGen/X86/setcc-logic.ll
+++ b/llvm/test/CodeGen/X86/setcc-logic.ll
@@ -440,11 +440,10 @@
define zeroext i1 @and_eq(i8 %a, i8 %b, i8 %c, i8 %d) nounwind {
; CHECK-LABEL: and_eq:
; CHECK: # BB#0:
-; CHECK-NEXT: cmpb %sil, %dil
-; CHECK-NEXT: sete %sil
-; CHECK-NEXT: cmpb %cl, %dl
+; CHECK-NEXT: xorl %esi, %edi
+; CHECK-NEXT: xorl %ecx, %edx
+; CHECK-NEXT: orb %dl, %dil
; CHECK-NEXT: sete %al
-; CHECK-NEXT: andb %sil, %al
; CHECK-NEXT: retq
%cmp1 = icmp eq i8 %a, %b
%cmp2 = icmp eq i8 %c, %d
@@ -455,11 +454,10 @@
define zeroext i1 @or_ne(i8 %a, i8 %b, i8 %c, i8 %d) nounwind {
; CHECK-LABEL: or_ne:
; CHECK: # BB#0:
-; CHECK-NEXT: cmpb %sil, %dil
-; CHECK-NEXT: setne %sil
-; CHECK-NEXT: cmpb %cl, %dl
+; CHECK-NEXT: xorl %esi, %edi
+; CHECK-NEXT: xorl %ecx, %edx
+; CHECK-NEXT: orb %dl, %dil
; CHECK-NEXT: setne %al
-; CHECK-NEXT: orb %sil, %al
; CHECK-NEXT: retq
%cmp1 = icmp ne i8 %a, %b
%cmp2 = icmp ne i8 %c, %d