[PATCH] D143593: [InstCombine] Don't fold freeze poison when it's used in shufflevector

[Manuel Brito via Phabricator via llvm-commits]

ManuelJBrito updated this revision to Diff 496587.
ManuelJBrito edited the summary of this revision.
ManuelJBrito added a comment.

Address comments


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D143593/new/

https://reviews.llvm.org/D143593

Files:
  llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
  llvm/test/Transforms/InstCombine/shufflevector_freezepoison.ll


Index: llvm/test/Transforms/InstCombine/shufflevector_freezepoison.ll
===================================================================
--- llvm/test/Transforms/InstCombine/shufflevector_freezepoison.ll
+++ llvm/test/Transforms/InstCombine/shufflevector_freezepoison.ll
@@ -4,7 +4,8 @@
 
 define <4 x double> @shuffle_op0_freeze_poison(<2 x double> %a) {
 ; CHECK-LABEL: @shuffle_op0_freeze_poison(
-; CHECK-NEXT:    [[SHUFFLE:%.*]] = shufflevector <2 x double> zeroinitializer, <2 x double> [[A:%.*]], <4 x i32> <i32 0, i32 1, i32 2, i32 3>
+; CHECK-NEXT:    [[B:%.*]] = freeze <2 x double> poison
+; CHECK-NEXT:    [[SHUFFLE:%.*]] = shufflevector <2 x double> [[B]], <2 x double> [[A:%.*]], <4 x i32> <i32 0, i32 1, i32 2, i32 3>
 ; CHECK-NEXT:    ret <4 x double> [[SHUFFLE]]
 ;
   %b = freeze <2 x double> poison
@@ -14,7 +15,8 @@
 
 define <4 x double> @shuffle_op1_freeze_poison(<2 x double> %a) {
 ; CHECK-LABEL: @shuffle_op1_freeze_poison(
-; CHECK-NEXT:    [[SHUFFLE:%.*]] = shufflevector <2 x double> [[A:%.*]], <2 x double> zeroinitializer, <4 x i32> <i32 0, i32 1, i32 2, i32 3>
+; CHECK-NEXT:    [[B:%.*]] = freeze <2 x double> poison
+; CHECK-NEXT:    [[SHUFFLE:%.*]] = shufflevector <2 x double> [[A:%.*]], <2 x double> [[B]], <4 x i32> <i32 0, i32 1, i32 2, i32 3>
 ; CHECK-NEXT:    ret <4 x double> [[SHUFFLE]]
 ;
   %b = freeze <2 x double> poison
@@ -24,8 +26,9 @@
 
 define <4 x double> @shuffle_op0_freeze_poison_use(<2 x double> %a) {
 ; CHECK-LABEL: @shuffle_op0_freeze_poison_use(
-; CHECK-NEXT:    call void @use(<2 x double> zeroinitializer)
-; CHECK-NEXT:    [[SHUFFLE:%.*]] = shufflevector <2 x double> zeroinitializer, <2 x double> [[A:%.*]], <4 x i32> <i32 0, i32 1, i32 2, i32 3>
+; CHECK-NEXT:    [[B:%.*]] = freeze <2 x double> poison
+; CHECK-NEXT:    call void @use(<2 x double> [[B]])
+; CHECK-NEXT:    [[SHUFFLE:%.*]] = shufflevector <2 x double> [[B]], <2 x double> [[A:%.*]], <4 x i32> <i32 0, i32 1, i32 2, i32 3>
 ; CHECK-NEXT:    ret <4 x double> [[SHUFFLE]]
 ;
   %b = freeze <2 x double> poison
@@ -36,8 +39,9 @@
 
 define <4 x double> @shuffle_op1_freeze_poison_use(<2 x double> %a) {
 ; CHECK-LABEL: @shuffle_op1_freeze_poison_use(
-; CHECK-NEXT:    call void @use(<2 x double> zeroinitializer)
-; CHECK-NEXT:    [[SHUFFLE:%.*]] = shufflevector <2 x double> [[A:%.*]], <2 x double> zeroinitializer, <4 x i32> <i32 0, i32 1, i32 2, i32 3>
+; CHECK-NEXT:    [[B:%.*]] = freeze <2 x double> poison
+; CHECK-NEXT:    call void @use(<2 x double> [[B]])
+; CHECK-NEXT:    [[SHUFFLE:%.*]] = shufflevector <2 x double> [[A:%.*]], <2 x double> [[B]], <4 x i32> <i32 0, i32 1, i32 2, i32 3>
 ; CHECK-NEXT:    ret <4 x double> [[SHUFFLE]]
 ;
   %b = freeze <2 x double> poison
@@ -48,8 +52,9 @@
 
 define <4 x double> @shuffle_op0_freeze_undef(<2 x double> %a) {
 ; CHECK-LABEL: @shuffle_op0_freeze_undef(
-; CHECK-NEXT:    call void @use(<2 x double> zeroinitializer)
-; CHECK-NEXT:    [[SHUFFLE:%.*]] = shufflevector <2 x double> zeroinitializer, <2 x double> [[A:%.*]], <4 x i32> <i32 0, i32 1, i32 2, i32 3>
+; CHECK-NEXT:    [[B:%.*]] = freeze <2 x double> undef
+; CHECK-NEXT:    call void @use(<2 x double> [[B]])
+; CHECK-NEXT:    [[SHUFFLE:%.*]] = shufflevector <2 x double> [[B]], <2 x double> [[A:%.*]], <4 x i32> <i32 0, i32 1, i32 2, i32 3>
 ; CHECK-NEXT:    ret <4 x double> [[SHUFFLE]]
 ;
   %b = freeze <2 x double> undef
@@ -60,8 +65,9 @@
 
 define <4 x double> @shuffle_op1_freeze_undef(<2 x double> %a) {
 ; CHECK-LABEL: @shuffle_op1_freeze_undef(
-; CHECK-NEXT:    call void @use(<2 x double> zeroinitializer)
-; CHECK-NEXT:    [[SHUFFLE:%.*]] = shufflevector <2 x double> [[A:%.*]], <2 x double> zeroinitializer, <4 x i32> <i32 0, i32 1, i32 2, i32 3>
+; CHECK-NEXT:    [[B:%.*]] = freeze <2 x double> undef
+; CHECK-NEXT:    call void @use(<2 x double> [[B]])
+; CHECK-NEXT:    [[SHUFFLE:%.*]] = shufflevector <2 x double> [[A:%.*]], <2 x double> [[B]], <4 x i32> <i32 0, i32 1, i32 2, i32 3>
 ; CHECK-NEXT:    ret <4 x double> [[SHUFFLE]]
 ;
   %b = freeze <2 x double> undef
Index: llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
===================================================================
--- llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
+++ llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
@@ -4014,8 +4014,17 @@
     return BestValue;
   };
 
-  if (match(Op0, m_Undef()))
+  if (match(Op0, m_Undef())) {
+    for (const auto *U : I.users()) {
+      // Don't fold freeze(undef/poison) if it's used has a vector operand in
+      // a shuffle. This may improve codegen for shuffles that allow
+      // unspecified inputs.
+      if (match(U, m_Shuffle(m_Value(), m_Specific(&I))) ||
+          match(U, m_Shuffle(m_Specific(&I), m_Value())))
+        return nullptr;
+    }
     return replaceInstUsesWith(I, getUndefReplacement(I.getType()));
+  }
 
   Constant *C;
   if (match(Op0, m_Constant(C)) && C->containsUndefOrPoisonElement()) {


-------------- next part --------------
A non-text attachment was scrubbed...
Name: D143593.496587.patch
Type: text/x-patch
Size: 4942 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20230210/13f7502e/attachment.bin>