InstCombine: Ensure select condition types are identical before merging

Selection conditions may be vectors or scalars.  Make sure InstCombine
doesn't indiscriminately assume that a select which is value dependent
on another select have identical select condition types.

This fixes PR22773.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@231156 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Transforms/InstCombine/InstCombineSelect.cpp b/lib/Transforms/InstCombine/InstCombineSelect.cpp
index dd0e65f2f6f486b27237c8afbb31b1b12c35b932..eff575ebcaab354f71900c1a3a10938aeaa7d6ac 100644 (file)
--- a/lib/Transforms/InstCombine/InstCombineSelect.cpp
+++ b/lib/Transforms/InstCombine/InstCombineSelect.cpp
@@ -1203,37 +1203,41 @@ Instruction *InstCombiner::visitSelectInst(SelectInst &SI) {
         return NV;
 
   if (SelectInst *TrueSI = dyn_cast<SelectInst>(TrueVal)) {
-    // select(C, select(C, a, b), c) -> select(C, a, c)
-    if (TrueSI->getCondition() == CondVal) {
-      if (SI.getTrueValue() == TrueSI->getTrueValue())
-        return nullptr;
-      SI.setOperand(1, TrueSI->getTrueValue());
-      return &SI;
-    }
-    // select(C0, select(C1, a, b), b) -> select(C0&C1, a, b)
-    // We choose this as normal form to enable folding on the And and shortening
-    // paths for the values (this helps GetUnderlyingObjects() for example).
-    if (TrueSI->getFalseValue() == FalseVal && TrueSI->hasOneUse()) {
-      Value *And = Builder->CreateAnd(CondVal, TrueSI->getCondition());
-      SI.setOperand(0, And);
-      SI.setOperand(1, TrueSI->getTrueValue());
-      return &SI;
+    if (TrueSI->getCondition()->getType() == CondVal->getType()) {
+      // select(C, select(C, a, b), c) -> select(C, a, c)
+      if (TrueSI->getCondition() == CondVal) {
+        if (SI.getTrueValue() == TrueSI->getTrueValue())
+          return nullptr;
+        SI.setOperand(1, TrueSI->getTrueValue());
+        return &SI;
+      }
+      // select(C0, select(C1, a, b), b) -> select(C0&C1, a, b)
+      // We choose this as normal form to enable folding on the And and shortening
+      // paths for the values (this helps GetUnderlyingObjects() for example).
+      if (TrueSI->getFalseValue() == FalseVal && TrueSI->hasOneUse()) {
+        Value *And = Builder->CreateAnd(CondVal, TrueSI->getCondition());
+        SI.setOperand(0, And);
+        SI.setOperand(1, TrueSI->getTrueValue());
+        return &SI;
+      }
     }
   }
   if (SelectInst *FalseSI = dyn_cast<SelectInst>(FalseVal)) {
-    // select(C, a, select(C, b, c)) -> select(C, a, c)
-    if (FalseSI->getCondition() == CondVal) {
-      if (SI.getFalseValue() == FalseSI->getFalseValue())
-        return nullptr;
-      SI.setOperand(2, FalseSI->getFalseValue());
-      return &SI;
-    }
-    // select(C0, a, select(C1, a, b)) -> select(C0|C1, a, b)
-    if (FalseSI->getTrueValue() == TrueVal && FalseSI->hasOneUse()) {
-      Value *Or = Builder->CreateOr(CondVal, FalseSI->getCondition());
-      SI.setOperand(0, Or);
-      SI.setOperand(2, FalseSI->getFalseValue());
-      return &SI;
+    if (FalseSI->getCondition()->getType() == CondVal->getType()) {
+      // select(C, a, select(C, b, c)) -> select(C, a, c)
+      if (FalseSI->getCondition() == CondVal) {
+        if (SI.getFalseValue() == FalseSI->getFalseValue())
+          return nullptr;
+        SI.setOperand(2, FalseSI->getFalseValue());
+        return &SI;
+      }
+      // select(C0, a, select(C1, a, b)) -> select(C0|C1, a, b)
+      if (FalseSI->getTrueValue() == TrueVal && FalseSI->hasOneUse()) {
+        Value *Or = Builder->CreateOr(CondVal, FalseSI->getCondition());
+        SI.setOperand(0, Or);
+        SI.setOperand(2, FalseSI->getFalseValue());
+        return &SI;
+      }
     }
   }
 

diff --git a/test/Transforms/InstCombine/select-select.ll b/test/Transforms/InstCombine/select-select.ll
index 65820acf07b89966670103e13a7ee35fa3667e95..768d1c47c20965688623e5381e624d49f02ba578 100644 (file)
--- a/test/Transforms/InstCombine/select-select.ll
+++ b/test/Transforms/InstCombine/select-select.ll
@@ -21,4 +21,14 @@ define float @foo2(float %a) #0 {
   ret float %f
 }
 
+; CHECK-LABEL: @foo3
+define <2 x i32> @foo3(<2 x i1> %vec_bool, i1 %bool, <2 x i32> %V) {
+; CHECK: %[[sel0:.*]] = select <2 x i1> %vec_bool, <2 x i32> zeroinitializer, <2 x i32> %V
+; CHECK: %[[sel1:.*]] = select i1 %bool, <2 x i32> %[[sel0]], <2 x i32> %V
+; CHECK: ret <2 x i32> %[[sel1]]
+  %sel0 = select <2 x i1> %vec_bool, <2 x i32> zeroinitializer, <2 x i32> %V
+  %sel1 = select i1 %bool, <2 x i32> %sel0, <2 x i32> %V
+  ret <2 x i32> %sel1
+}
+
 attributes #0 = { nounwind readnone ssp uwtable }