Fix another infinite loop in Reassociate caused by Constant::isZero().

Not all zero vectors are ConstantDataVector's.

llvm-svn: 253723

2 files changed, 23 insertions, 0 deletions

diff --git a/llvm/lib/IR/Constants.cpp b/llvm/lib/IR/Constants.cpp
index b237c913dcf..d79fb3e7b0b 100644
--- a/llvm/lib/IR/Constants.cpp
+++ b/llvm/lib/IR/Constants.cpp
@@ -53,6 +53,11 @@ bool Constant::isNegativeZeroValue() const {
       if (SplatCFP && SplatCFP->isZero() && SplatCFP->isNegative())
         return true;
 
+  if (const ConstantVector *CV = dyn_cast<ConstantVector>(this))
+    if (ConstantFP *SplatCFP = dyn_cast_or_null<ConstantFP>(CV->getSplatValue()))
+      if (SplatCFP && SplatCFP->isZero() && SplatCFP->isNegative())
+        return true;
+
   // We've already handled true FP case; any other FP vectors can't represent -0.0.
   if (getType()->isFPOrFPVectorTy())
     return false;
@@ -74,6 +79,11 @@ bool Constant::isZeroValue() const {
       if (SplatCFP && SplatCFP->isZero())
         return true;
 
+  if (const ConstantVector *CV = dyn_cast<ConstantVector>(this))
+    if (ConstantFP *SplatCFP = dyn_cast_or_null<ConstantFP>(CV->getSplatValue()))
+      if (SplatCFP && SplatCFP->isZero())
+        return true;
+
   // Otherwise, just use +0.0.
   return isNullValue();
 }
diff --git a/llvm/test/Transforms/Reassociate/fp-expr.ll b/llvm/test/Transforms/Reassociate/fp-expr.ll
index ee927069812..5af3b1991c9 100644
--- a/llvm/test/Transforms/Reassociate/fp-expr.ll
+++ b/llvm/test/Transforms/Reassociate/fp-expr.ll
@@ -12,6 +12,19 @@ define void @test1() {
   ret void
 }
 
+define half @test2() {
+; CHECK-LABEL: @test2
+; CHECK: fsub
+; CHECK: fsub
+; CHECK: fadd
+  %tmp15 = fsub fast half undef, undef
+  %tmp17 = fsub fast half undef, %tmp15
+  %tmp18 = fadd fast half undef, %tmp17
+  ret half %tmp18
+}
+
+
+
 ; Function Attrs: optsize
 declare <4 x float> @blam()