[PATCH] D36170: LSR: Fix PR33514

[Evgeny Stupachenko via Phabricator via llvm-commits]

evstupac created this revision.
Herald added a subscriber: mzolotukhin.

The patch restrict multiplication of ICmpZero formula by any constant if there is a pointer type register (p) in the formula.
If not restricted it can potentially cause expand of SCEV :  C * p, which is undefined (if C != 1 or 0).


Repository:
  rL LLVM

https://reviews.llvm.org/D36170

Files:
  lib/Transforms/Scalar/LoopStrengthReduce.cpp
  test/Transforms/LoopStrengthReduce/pr27056.ll


Index: lib/Transforms/Scalar/LoopStrengthReduce.cpp
===================================================================
--- lib/Transforms/Scalar/LoopStrengthReduce.cpp
+++ lib/Transforms/Scalar/LoopStrengthReduce.cpp
@@ -3646,6 +3646,12 @@
   // Don't do this if there is more than one offset.
   if (LU.MinOffset != LU.MaxOffset) return;
 
+  // Check if transformation is valid. It is illegal to multiply pointer.
+  if (Base.ScaledReg && Base.ScaledReg->getType()->isPointerTy())
+    return;
+  for (const SCEV *BaseReg : Base.BaseRegs)
+    if (BaseReg->getType()->isPointerTy())
+      return;
   assert(!Base.BaseGV && "ICmpZero use is not legal!");
 
   // Check each interesting stride.
Index: test/Transforms/LoopStrengthReduce/pr27056.ll
===================================================================
--- test/Transforms/LoopStrengthReduce/pr27056.ll
+++ test/Transforms/LoopStrengthReduce/pr27056.ll
@@ -45,6 +45,7 @@
 ; CHECK-LABEL: define void @b_copy_ctor(
 ; CHECK:       catchpad
 ; CHECK-NEXT:  icmp eq %struct.L
-; CHECK-NEXT:  getelementptr {{.*}} i64 sub (i64 0, i64 ptrtoint (%struct.L* @GV2 to i64))
+; CHECK-NEXT:  %4 = sub i64 0, %1
+; CHECK-NEXT:  getelementptr {{.*}} getelementptr inbounds (%struct.L, %struct.L* @GV2, i32 0, i32 0), i64 %4
 
 declare void @a_copy_ctor()


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