[llvm] 822c749 - [LV] Shrink operands before creating new instr to force eval order.

[Florian Hahn via llvm-commits]

Author: Florian Hahn
Date: 2023-07-30T17:16:37+01:00
New Revision: 822c749aec69ace75bd3923a4c850e2fd2e34fb1

URL: https://github.com/llvm/llvm-project/commit/822c749aec69ace75bd3923a4c850e2fd2e34fb1
DIFF: https://github.com/llvm/llvm-project/commit/822c749aec69ace75bd3923a4c850e2fd2e34fb1.diff

LOG: [LV] Shrink operands before creating new instr to force eval order.

Shrink operands before creating the new instruction to make sure the
same evaluation order is used on all platforms. This fixes buildbot
failures due to different argument evaluation order on different
systems.

Added: 
    

Modified: 
    llvm/lib/Transforms/Vectorize/LoopVectorize.cpp

Removed: 
    


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diff  --git a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
index d7e40e8ef978c6..7bdeccec5cd1fd 100644
--- a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
+++ b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
@@ -3595,21 +3595,22 @@ void InnerLoopVectorizer::truncateToMinimalBitwidths(VPTransformState &State) {
       // unfortunately.
       Value *NewI = nullptr;
       if (auto *BO = dyn_cast<BinaryOperator>(I)) {
-        NewI = B.CreateBinOp(BO->getOpcode(), ShrinkOperand(BO->getOperand(0)),
-                             ShrinkOperand(BO->getOperand(1)));
+        Value *Op0 = ShrinkOperand(BO->getOperand(0));
+        Value *Op1 = ShrinkOperand(BO->getOperand(1));
+        NewI = B.CreateBinOp(BO->getOpcode(), Op0, Op1);
 
         // Any wrapping introduced by shrinking this operation shouldn't be
         // considered undefined behavior. So, we can't unconditionally copy
         // arithmetic wrapping flags to NewI.
         cast<BinaryOperator>(NewI)->copyIRFlags(I, /*IncludeWrapFlags=*/false);
       } else if (auto *CI = dyn_cast<ICmpInst>(I)) {
-        NewI =
-            B.CreateICmp(CI->getPredicate(), ShrinkOperand(CI->getOperand(0)),
-                         ShrinkOperand(CI->getOperand(1)));
+        Value *Op0 = ShrinkOperand(BO->getOperand(0));
+        Value *Op1 = ShrinkOperand(BO->getOperand(1));
+        NewI = B.CreateICmp(CI->getPredicate(), Op0, Op1);
       } else if (auto *SI = dyn_cast<SelectInst>(I)) {
-        NewI = B.CreateSelect(SI->getCondition(),
-                              ShrinkOperand(SI->getTrueValue()),
-                              ShrinkOperand(SI->getFalseValue()));
+        Value *TV = ShrinkOperand(SI->getTrueValue());
+        Value *FV = ShrinkOperand(SI->getFalseValue());
+        NewI = B.CreateSelect(SI->getCondition(), TV, FV);
       } else if (auto *CI = dyn_cast<CastInst>(I)) {
         switch (CI->getOpcode()) {
         default: