[InstCombine] Update instcombine for vectorOps to use new shufflevector semantics

This patch updates the transformations in InstCombineVectorOps to use the new
hufflevector semantics that say that undefined values in the mask yield poison.

To prevent miscompilations we have to match with m_Poison instead of m_Undef.
Otherwise, we might introduce poison where there was previously undef.

Differential Revision: https://reviews.llvm.org/D150039

diff --git a/llvm/lib/Transforms/InstCombine/InstCombineVectorOps.cpp b/llvm/lib/Transforms/InstCombine/InstCombineVectorOps.cpp
index d398406..4bab964 100644 (file)
--- a/llvm/lib/Transforms/InstCombine/InstCombineVectorOps.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineVectorOps.cpp
@@ -640,11 +640,11 @@ static bool collectSingleShuffleElements(Value *V, Value *LHS, Value *RHS,
       return false;
     unsigned InsertedIdx = cast<ConstantInt>(IdxOp)->getZExtValue();
 
-    if (isa<UndefValue>(ScalarOp)) {  // inserting undef into vector.
+    if (isa<PoisonValue>(ScalarOp)) {  // inserting poison into vector.
       // We can handle this if the vector we are inserting into is
       // transitively ok.
       if (collectSingleShuffleElements(VecOp, LHS, RHS, Mask)) {
-        // If so, update the mask to reflect the inserted undef.
+        // If so, update the mask to reflect the inserted poison.
         Mask[InsertedIdx] = -1;
         return true;
       }
@@ -1240,11 +1240,11 @@ static Instruction *foldInsSequenceIntoSplat(InsertElementInst &InsElt) {
   if (FirstIE == &InsElt)
     return nullptr;
 
-  // If we are not inserting into an undef vector, make sure we've seen an
+  // If we are not inserting into a poison vector, make sure we've seen an
   // insert into every element.
   // TODO: If the base vector is not undef, it might be better to create a splat
   //       and then a select-shuffle (blend) with the base vector.
-  if (!match(FirstIE->getOperand(0), m_Undef()))
+  if (!match(FirstIE->getOperand(0), m_Poison()))
     if (!ElementPresent.all())
       return nullptr;
 
@@ -1255,7 +1255,7 @@ static Instruction *foldInsSequenceIntoSplat(InsertElementInst &InsElt) {
   if (!cast<ConstantInt>(FirstIE->getOperand(2))->isZero())
     FirstIE = InsertElementInst::Create(PoisonVec, SplatVal, Zero, "", &InsElt);
 
-  // Splat from element 0, but replace absent elements with undef in the mask.
+  // Splat from element 0, but replace absent elements with poison in the mask.
   SmallVector<int, 16> Mask(NumElements, 0);
   for (unsigned i = 0; i != NumElements; ++i)
     if (!ElementPresent[i])
@@ -3060,7 +3060,7 @@ Instruction *InstCombinerImpl::visitShuffleVectorInst(ShuffleVectorInst &SVI) {
   for (unsigned i = 0; i < VWidth; ++i) {
     int eltMask;
     if (Mask[i] < 0) {
-      // This element is an undef value.
+      // This element is a poison value.
       eltMask = -1;
     } else if (Mask[i] < (int)LHSWidth) {
       // This element is from left hand side vector operand.
@@ -3069,27 +3069,27 @@ Instruction *InstCombinerImpl::visitShuffleVectorInst(ShuffleVectorInst &SVI) {
       // new mask value for the element.
       if (newLHS != LHS) {
         eltMask = LHSMask[Mask[i]];
-        // If the value selected is an undef value, explicitly specify it
+        // If the value selected is an poison value, explicitly specify it
         // with a -1 mask value.
-        if (eltMask >= (int)LHSOp0Width && isa<UndefValue>(LHSOp1))
+        if (eltMask >= (int)LHSOp0Width && isa<PoisonValue>(LHSOp1))
           eltMask = -1;
       } else
         eltMask = Mask[i];
     } else {
       // This element is from right hand side vector operand
       //
-      // If the value selected is an undef value, explicitly specify it
+      // If the value selected is a poison value, explicitly specify it
       // with a -1 mask value. (case 1)
-      if (match(RHS, m_Undef()))
+      if (match(RHS, m_Poison()))
         eltMask = -1;
       // If RHS is going to be replaced (case 3 or 4), calculate the
       // new mask value for the element.
       else if (newRHS != RHS) {
         eltMask = RHSMask[Mask[i]-LHSWidth];
-        // If the value selected is an undef value, explicitly specify it
+        // If the value selected is an poison value, explicitly specify it
         // with a -1 mask value.
         if (eltMask >= (int)RHSOp0Width) {
-          assert(match(RHSShuffle->getOperand(1), m_Undef()) &&
+          assert(match(RHSShuffle->getOperand(1), m_Poison()) &&
                  "should have been check above");
           eltMask = -1;
         }
@@ -3120,7 +3120,7 @@ Instruction *InstCombinerImpl::visitShuffleVectorInst(ShuffleVectorInst &SVI) {
   // or is a splat, do the replacement.
   if (isSplat || newMask == LHSMask || newMask == RHSMask || newMask == Mask) {
     if (!newRHS)
-      newRHS = UndefValue::get(newLHS->getType());
+      newRHS = PoisonValue::get(newLHS->getType());
     return new ShuffleVectorInst(newLHS, newRHS, newMask);
   }
 

diff --git a/llvm/test/Transforms/InstCombine/broadcast.ll b/llvm/test/Transforms/InstCombine/broadcast.ll
index 6f82043..5e5c3d6 100644 (file)
--- a/llvm/test/Transforms/InstCombine/broadcast.ll
+++ b/llvm/test/Transforms/InstCombine/broadcast.ll
@@ -76,8 +76,9 @@ define <4 x float> @good5(float %v) {
 
 define <4 x float> @splat_undef1(float %arg) {
 ; CHECK-LABEL: @splat_undef1(
-; CHECK-NEXT:    [[TMP1:%.*]] = insertelement <4 x float> poison, float [[ARG:%.*]], i64 0
-; CHECK-NEXT:    [[T6:%.*]] = shufflevector <4 x float> [[TMP1]], <4 x float> poison, <4 x i32> <i32 poison, i32 0, i32 0, i32 0>
+; CHECK-NEXT:    [[T4:%.*]] = insertelement <4 x float> undef, float [[ARG:%.*]], i64 1
+; CHECK-NEXT:    [[T5:%.*]] = insertelement <4 x float> [[T4]], float [[ARG:%.*]], i64 2
+; CHECK-NEXT:    [[T6:%.*]] = insertelement <4 x float> [[T5]], float [[ARG:%.*]], i64 3
 ; CHECK-NEXT:    ret <4 x float> [[T6]]
 ;
   %t = insertelement <4 x float> undef, float %arg, i32 1
@@ -92,7 +93,8 @@ define <4 x float> @splat_undef1(float %arg) {
 define <4 x float> @splat_undef2(float %arg) {
 ; CHECK-LABEL: @splat_undef2(
 ; CHECK-NEXT:    [[T:%.*]] = insertelement <4 x float> undef, float [[ARG:%.*]], i64 0
-; CHECK-NEXT:    [[T6:%.*]] = shufflevector <4 x float> [[T]], <4 x float> poison, <4 x i32> <i32 0, i32 poison, i32 0, i32 0>
+; CHECK-NEXT:    [[T5:%.*]] = insertelement <4 x float> [[T]], float [[ARG:%.*]], i64 2
+; CHECK-NEXT:    [[T6:%.*]] = insertelement <4 x float> [[T5]], float [[ARG:%.*]], i64 3
 ; CHECK-NEXT:    ret <4 x float> [[T6]]
 ;
   %t = insertelement <4 x float> undef, float %arg, i32 0
@@ -131,8 +133,9 @@ define <1 x float> @bad4(float %arg) {
 define <4 x float> @splat_undef3(float %arg) {
 ; CHECK-LABEL: @splat_undef3(
 ; CHECK-NEXT:    [[T:%.*]] = insertelement <4 x float> undef, float [[ARG:%.*]], i64 0
-; CHECK-NEXT:    [[T4:%.*]] = shufflevector <4 x float> [[T]], <4 x float> poison, <4 x i32> <i32 0, i32 0, i32 poison, i32 poison>
-; CHECK-NEXT:    [[T6:%.*]] = shufflevector <4 x float> [[T]], <4 x float> poison, <4 x i32> zeroinitializer
+; CHECK-NEXT:    [[T4:%.*]] = insertelement <4 x float> [[T]], float [[ARG:%.*]], i64 1
+; CHECK-NEXT:    [[T5:%.*]] = insertelement <4 x float> [[T4]], float [[ARG:%.*]], i64 2
+; CHECK-NEXT:    [[T6:%.*]] = insertelement <4 x float> [[T5]], float [[ARG:%.*]], i64 3
 ; CHECK-NEXT:    [[T7:%.*]] = fadd <4 x float> [[T6]], [[T4]]
 ; CHECK-NEXT:    ret <4 x float> [[T7]]
 ;

diff --git a/llvm/test/Transforms/InstCombine/vec_shuffle-inseltpoison.ll b/llvm/test/Transforms/InstCombine/vec_shuffle-inseltpoison.ll
index 65f1ab2..f664c3e 100644 (file)
--- a/llvm/test/Transforms/InstCombine/vec_shuffle-inseltpoison.ll
+++ b/llvm/test/Transforms/InstCombine/vec_shuffle-inseltpoison.ll
@@ -152,7 +152,7 @@ define <4 x i32> @test10(<4 x i32> %t5) {
 
 define <8 x i8> @test11(<16 x i8> %t6) {
 ; CHECK-LABEL: @test11(
-; CHECK-NEXT:    [[T3:%.*]] = shufflevector <16 x i8> [[T6:%.*]], <16 x i8> undef, <8 x i32> <i32 0, i32 1, i32 2, i32 3, i32 4, i32 5, i32 6, i32 7>
+; CHECK-NEXT:    [[T3:%.*]] = shufflevector <16 x i8> [[T6:%.*]], <16 x i8> poison, <8 x i32> <i32 0, i32 1, i32 2, i32 3, i32 4, i32 5, i32 6, i32 7>
 ; CHECK-NEXT:    ret <8 x i8> [[T3]]
 ;
   %t1 = shufflevector <16 x i8> %t6, <16 x i8> poison, <4 x i32> <i32 0, i32 1, i32 2, i32 3>

diff --git a/llvm/test/Transforms/InstCombine/vec_shuffle.ll b/llvm/test/Transforms/InstCombine/vec_shuffle.ll
index b67c0de..0081da2 100644 (file)
--- a/llvm/test/Transforms/InstCombine/vec_shuffle.ll
+++ b/llvm/test/Transforms/InstCombine/vec_shuffle.ll
@@ -158,7 +158,7 @@ define <4 x i32> @test10(<4 x i32> %t5) {
 
 define <8 x i8> @test11(<16 x i8> %t6) {
 ; CHECK-LABEL: @test11(
-; CHECK-NEXT:    [[T3:%.*]] = shufflevector <16 x i8> [[T6:%.*]], <16 x i8> undef, <8 x i32> <i32 0, i32 1, i32 2, i32 3, i32 4, i32 5, i32 6, i32 7>
+; CHECK-NEXT:    [[T3:%.*]] = shufflevector <16 x i8> [[T6:%.*]], <16 x i8> poison, <8 x i32> <i32 0, i32 1, i32 2, i32 3, i32 4, i32 5, i32 6, i32 7>
 ; CHECK-NEXT:    ret <8 x i8> [[T3]]
 ;
   %t1 = shufflevector <16 x i8> %t6, <16 x i8> undef, <4 x i32> <i32 0, i32 1, i32 2, i32 3>

diff --git a/llvm/test/Transforms/SLPVectorizer/X86/pr49081.ll b/llvm/test/Transforms/SLPVectorizer/X86/pr49081.ll
index 9be8fb7..740bf71 100644 (file)
--- a/llvm/test/Transforms/SLPVectorizer/X86/pr49081.ll
+++ b/llvm/test/Transforms/SLPVectorizer/X86/pr49081.ll
@@ -8,7 +8,7 @@ define dso_local <4 x float> @foo(<4 x i32> %0) {
 ; CHECK-NEXT:    [[TMP2:%.*]] = extractelement <4 x i32> [[TMP0:%.*]], i64 1
 ; CHECK-NEXT:    [[TMP3:%.*]] = sitofp i32 [[TMP2]] to float
 ; CHECK-NEXT:    [[TMP4:%.*]] = insertelement <4 x float> undef, float [[TMP3]], i64 0
-; CHECK-NEXT:    [[TMP5:%.*]] = shufflevector <4 x float> [[TMP4]], <4 x float> poison, <4 x i32> <i32 0, i32 0, i32 poison, i32 poison>
+; CHECK-NEXT:    [[TMP5:%.*]] = insertelement <4 x float> [[TMP4]], float [[TMP3]], i64 1
 ; CHECK-NEXT:    [[TMP6:%.*]] = shufflevector <4 x i32> [[TMP0]], <4 x i32> poison, <2 x i32> <i32 2, i32 3>
 ; CHECK-NEXT:    [[TMP7:%.*]] = sitofp <2 x i32> [[TMP6]] to <2 x float>
 ; CHECK-NEXT:    [[TMP8:%.*]] = shufflevector <2 x float> [[TMP7]], <2 x float> poison, <4 x i32> <i32 0, i32 1, i32 poison, i32 poison>