[llvm] r275532 - [IR] andIRFlags and copyIRFlags needs to handle GEP

[David Majnemer via llvm-commits]

Author: majnemer
Date: Fri Jul 15 00:02:31 2016
New Revision: 275532

URL: http://llvm.org/viewvc/llvm-project?rev=275532&view=rev
Log:
[IR] andIRFlags and copyIRFlags needs to handle GEP

We didn't consider the inbounds flag on GEPs leading to downstream users
introducing UB.

This fixes PR28562.

Added:
    llvm/trunk/test/Transforms/GVN/pr28562.ll
Modified:
    llvm/trunk/lib/IR/Instruction.cpp

Modified: llvm/trunk/lib/IR/Instruction.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/IR/Instruction.cpp?rev=275532&r1=275531&r2=275532&view=diff
==============================================================================
--- llvm/trunk/lib/IR/Instruction.cpp (original)
+++ llvm/trunk/lib/IR/Instruction.cpp Fri Jul 15 00:02:31 2016
@@ -232,6 +232,10 @@ void Instruction::copyIRFlags(const Valu
   if (auto *FP = dyn_cast<FPMathOperator>(V))
     if (isa<FPMathOperator>(this))
       copyFastMathFlags(FP->getFastMathFlags());
+
+  if (auto *SrcGEP = dyn_cast<GetElementPtrInst>(V))
+    if (auto *DestGEP = dyn_cast<GetElementPtrInst>(this))
+      DestGEP->setIsInBounds(SrcGEP->isInBounds() | DestGEP->isInBounds());
 }
 
 void Instruction::andIRFlags(const Value *V) {
@@ -253,6 +257,10 @@ void Instruction::andIRFlags(const Value
       copyFastMathFlags(FM);
     }
   }
+
+  if (auto *SrcGEP = dyn_cast<GetElementPtrInst>(V))
+    if (auto *DestGEP = dyn_cast<GetElementPtrInst>(this))
+      DestGEP->setIsInBounds(SrcGEP->isInBounds() & DestGEP->isInBounds());
 }
 
 const char *Instruction::getOpcodeName(unsigned OpCode) {

Added: llvm/trunk/test/Transforms/GVN/pr28562.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/GVN/pr28562.ll?rev=275532&view=auto
==============================================================================
--- llvm/trunk/test/Transforms/GVN/pr28562.ll (added)
+++ llvm/trunk/test/Transforms/GVN/pr28562.ll Fri Jul 15 00:02:31 2016
@@ -0,0 +1,9 @@
+; RUN: opt -S -gvn < %s | FileCheck %s
+define i32* @test1(i32* %a) {
+  %x1 = getelementptr inbounds i32, i32* %a, i32 10
+  %x2 = getelementptr i32, i32* %a, i32 10
+  ret i32* %x2
+; CHECK-LABEL: @test1(
+; CHECK: %[[x:.*]] = getelementptr i32, i32* %a, i32 10
+; CHECK: ret i32* %[[x]]
+}