[llvm] r245365 - [InstSimplify] Don't assume getAggregateElement will succeed

[David Majnemer via llvm-commits]

Author: majnemer
Date: Tue Aug 18 17:07:25 2015
New Revision: 245365

URL: http://llvm.org/viewvc/llvm-project?rev=245365&view=rev
Log:
[InstSimplify] Don't assume getAggregateElement will succeed

It isn't always possible to get a value from getAggregateElement.
This fixes PR24488.

Modified:
    llvm/trunk/lib/Analysis/InstructionSimplify.cpp
    llvm/trunk/lib/Analysis/VectorUtils.cpp
    llvm/trunk/test/Transforms/InstSimplify/2011-09-05-InsertExtractValue.ll

Modified: llvm/trunk/lib/Analysis/InstructionSimplify.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/InstructionSimplify.cpp?rev=245365&r1=245364&r2=245365&view=diff
==============================================================================
--- llvm/trunk/lib/Analysis/InstructionSimplify.cpp (original)
+++ llvm/trunk/lib/Analysis/InstructionSimplify.cpp Tue Aug 18 17:07:25 2015
@@ -3578,11 +3578,6 @@ static Value *SimplifyExtractElementInst
     unsigned IndexVal = IdxC->getZExtValue();
     unsigned VectorWidth = Vec->getType()->getVectorNumElements();
 
-    // If this is extracting an invalid index, turn this into undef, to avoid
-    // crashing the code below.
-    if (IndexVal >= VectorWidth)
-      return UndefValue::get(Vec->getType()->getVectorElementType());
-
     if (Value *Elt = findScalarElement(Vec, IndexVal))
       return Elt;
   }

Modified: llvm/trunk/lib/Analysis/VectorUtils.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/VectorUtils.cpp?rev=245365&r1=245364&r2=245365&view=diff
==============================================================================
--- llvm/trunk/lib/Analysis/VectorUtils.cpp (original)
+++ llvm/trunk/lib/Analysis/VectorUtils.cpp Tue Aug 18 17:07:25 2015
@@ -398,10 +398,10 @@ Value *llvm::findScalarElement(Value *V,
 
   // Extract a value from a vector add operation with a constant zero.
   Value *Val = nullptr; Constant *Con = nullptr;
-  if (match(V, m_Add(m_Value(Val), m_Constant(Con)))) {
-    if (Con->getAggregateElement(EltNo)->isNullValue())
-      return findScalarElement(Val, EltNo);
-  }
+  if (match(V, m_Add(m_Value(Val), m_Constant(Con))))
+    if (Constant *Elt = Con->getAggregateElement(EltNo))
+      if (Elt->isNullValue())
+        return findScalarElement(Val, EltNo);
 
   // Otherwise, we don't know.
   return nullptr;

Modified: llvm/trunk/test/Transforms/InstSimplify/2011-09-05-InsertExtractValue.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstSimplify/2011-09-05-InsertExtractValue.ll?rev=245365&r1=245364&r2=245365&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/InstSimplify/2011-09-05-InsertExtractValue.ll (original)
+++ llvm/trunk/test/Transforms/InstSimplify/2011-09-05-InsertExtractValue.ll Tue Aug 18 17:07:25 2015
@@ -36,3 +36,13 @@ define i32 @test3(i32 %a, float %b) {
 ; CHECK-LABEL: @test3(
 ; CHECK: ret i32 %a
 }
+
+define i8 @test4(<8 x i8> %V) {
+  %add     = add <8 x i8> %V, bitcast (double 0x319BEB8FD172E36 to <8 x i8>)
+  %extract = extractelement <8 x i8> %add, i32 6
+  ret i8 %extract
+; CHECK-LABEL: @test4(
+; CHECK: %[[add:.*]] = add <8 x i8> %V, bitcast (<1 x double> <double 0x319BEB8FD172E36> to <8 x i8>)
+; CHECK-NEXT: %[[extract:.*]] = extractelement <8 x i8> %[[add]], i32 6
+; CHECK-NEXT: ret i8 %[[extract]]
+}