[CVP] Don't assume Constants of type i1 can be known to be true or false

CVP wants to analyze the condition operand of a select along an edge.
It succeeds in getting back a Constant but not a ConstantInt.  Instead,
it gets a ConstantExpr.  It then assumes that the Constant must be equal
to false because it isn't equal to true.

Instead, perform an additional comparison.

This fixes PR23752.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@239217 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp b/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp
index d1302c6e22f4986412538841e8a1103d783132d4..79624b2e4c4752d54f50a9b70862b67926ee2ecb 100644 (file)
--- a/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp
+++ b/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp
@@ -113,10 +113,11 @@ bool CorrelatedValuePropagation::processPHI(PHINode *P) {
 
       Value *Condition = SI->getCondition();
       if (!Condition->getType()->isVectorTy()) {
-        if (Constant *C = LVI->getConstantOnEdge(Condition, P->getIncomingBlock(i), BB, P)) {
-          if (C == ConstantInt::getTrue(Condition->getType())) {
+        if (Constant *C = LVI->getConstantOnEdge(
+                Condition, P->getIncomingBlock(i), BB, P)) {
+          if (C->isOneValue()) {
             V = SI->getTrueValue();
-          } else {
+          } else if (C->isZeroValue()) {
             V = SI->getFalseValue();
           }
           // Once LVI learns to handle vector types, we could also add support

diff --git a/test/Transforms/CorrelatedValuePropagation/select.ll b/test/Transforms/CorrelatedValuePropagation/select.ll
index 5501438f690f5ca26c9acca35064e9a3c5ae2826..d88e3e462a205de8a8d6bac4670d20608c5f13a8 100644 (file)
--- a/test/Transforms/CorrelatedValuePropagation/select.ll
+++ b/test/Transforms/CorrelatedValuePropagation/select.ll
@@ -51,3 +51,25 @@ else:
   ret i8 %b
 }
 
+@c = global i32 0, align 4
+@b = global i32 0, align 4
+
+; CHECK-LABEL: @PR23752(
+define i32 @PR23752() {
+entry:
+  br label %for.body
+
+for.body:
+  %phi = phi i32 [ 0, %entry ], [ %sel, %for.body ]
+  %sel = select i1 icmp sgt (i32* @b, i32* @c), i32 %phi, i32 1
+  %cmp = icmp ne i32 %sel, 1
+  br i1 %cmp, label %for.body, label %if.end
+
+; CHECK:      %[[sel:.*]] = select i1 icmp sgt (i32* @b, i32* @c), i32 0, i32 1
+; CHECK-NEXT: %[[cmp:.*]] = icmp ne i32 %[[sel]], 1
+; CHECK-NEXT: br i1 %[[cmp]]
+
+if.end:
+  ret i32 %sel
+; CHECK: ret i32 %[[sel]]
+}