From: Sanjay Patel <spatel@rotateright.com>
Date: Thu, 3 Sep 2015 16:36:16 +0000 (+0000)
Subject: [x86] enable machine combiner reassociations for scalar 'xor' insts
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=eb8298cfe10827a611440bed1a3cdf2453c4e093;p=llvm

[x86] enable machine combiner reassociations for scalar 'xor' insts


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@246781 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/Target/X86/X86InstrInfo.cpp b/lib/Target/X86/X86InstrInfo.cpp
index cf9d8a8aac3..8b883162999 100644
--- a/lib/Target/X86/X86InstrInfo.cpp
+++ b/lib/Target/X86/X86InstrInfo.cpp
@@ -6401,6 +6401,10 @@ static bool isAssociativeAndCommutative(const MachineInstr &Inst) {
   case X86::OR16rr:
   case X86::OR32rr:
   case X86::OR64rr:
+  case X86::XOR8rr:
+  case X86::XOR16rr:
+  case X86::XOR32rr:
+  case X86::XOR64rr:
   case X86::IMUL16rr:
   case X86::IMUL32rr:
   case X86::IMUL64rr:
diff --git a/test/CodeGen/X86/machine-combiner-int.ll b/test/CodeGen/X86/machine-combiner-int.ll
index 37e8e59b647..4a1ba1a980a 100644
--- a/test/CodeGen/X86/machine-combiner-int.ll
+++ b/test/CodeGen/X86/machine-combiner-int.ll
@@ -145,3 +145,50 @@ define i64 @reassociate_ors_i64(i64 %x0, i64 %x1, i64 %x2, i64 %x3) {
   ret i64 %t2
 }
 
+; Verify that integer 'xors' are reassociated. The first 'xor' in
+; each test should be independent of the result of the preceding sub.
+
+define i8 @reassociate_xors_i8(i8 %x0, i8 %x1, i8 %x2, i8 %x3) {
+; CHECK-LABEL: reassociate_xors_i8:
+; CHECK:       # BB#0:
+; CHECK-NEXT:    subb  %sil, %dil
+; CHECK-NEXT:    xorb  %cl, %dl
+; CHECK-NEXT:    xorb  %dil, %dl
+; CHECK_NEXT:    movb  %dx, %ax
+; CHECK_NEXT:    retq
+  %t0 = sub i8 %x0, %x1
+  %t1 = xor i8 %x2, %t0
+  %t2 = xor i8 %x3, %t1
+  ret i8 %t2
+}
+
+; TODO: No way to test i16? These appear to always get promoted to i32.
+
+define i32 @reassociate_xors_i32(i32 %x0, i32 %x1, i32 %x2, i32 %x3) {
+; CHECK-LABEL: reassociate_xors_i32:
+; CHECK:       # BB#0:
+; CHECK-NEXT:    subl  %esi, %edi
+; CHECK-NEXT:    xorl  %ecx, %edx
+; CHECK-NEXT:    xorl  %edi, %edx
+; CHECK_NEXT:    movl  %edx, %eax
+; CHECK_NEXT:    retq
+  %t0 = sub i32 %x0, %x1
+  %t1 = xor i32 %x2, %t0
+  %t2 = xor i32 %x3, %t1
+  ret i32 %t2
+}
+
+define i64 @reassociate_xors_i64(i64 %x0, i64 %x1, i64 %x2, i64 %x3) {
+; CHECK-LABEL: reassociate_xors_i64:
+; CHECK:       # BB#0:
+; CHECK-NEXT:    subq  %rsi, %rdi
+; CHECK-NEXT:    xorq  %rcx, %rdx
+; CHECK-NEXT:    xorq  %rdi, %rdx
+; CHECK-NEXT:    movq  %rdx, %rax
+; CHECK_NEXT:    retq
+  %t0 = sub i64 %x0, %x1
+  %t1 = xor i64 %x2, %t0
+  %t2 = xor i64 %x3, %t1
+  ret i64 %t2
+}
+