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List: llvm-commits
Subject: [llvm-commits] [llvm] r92354 - in /llvm/trunk:
From: Chris Lattner <sabre () nondot ! org>
Date: 2009-12-31 8:33:49
Message-ID: 200912310833.nBV8XnH2031199 () zion ! cs ! uiuc ! edu
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Author: lattner
Date: Thu Dec 31 02:33:49 2009
New Revision: 92354
URL: http://llvm.org/viewvc/llvm-project?rev=92354&view=rev
Log:
simple fix for an incorrect factoring which causes a
miscompilation, PR5458.
Modified:
llvm/trunk/lib/Transforms/Scalar/Reassociate.cpp
llvm/trunk/test/Transforms/Reassociate/basictest.ll
Modified: llvm/trunk/lib/Transforms/Scalar/Reassociate.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/Reassociate.cpp?rev=92354&r1=92353&r2=92354&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/Reassociate.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/Reassociate.cpp Thu Dec 31 02:33:49 2009
@@ -714,6 +714,10 @@
// To efficiently find this, we count the number of times a factor occurs
// for any ADD operands that are MULs.
DenseMap<Value*, unsigned> FactorOccurrences;
+
+ // Keep track of each multiply we see, to avoid triggering on (X*4)+(X*4)
+ // where they are actually the same multiply.
+ SmallPtrSet<BinaryOperator*, 4> Multiplies;
unsigned MaxOcc = 0;
Value *MaxOccVal = 0;
for (unsigned i = 0, e = Ops.size(); i != e; ++i) {
@@ -721,6 +725,9 @@
if (BOp == 0 || BOp->getOpcode() != Instruction::Mul || !BOp->use_empty())
continue;
+ // If we've already seen this multiply, don't revisit it.
+ if (!Multiplies.insert(BOp)) continue;
+
// Compute all of the factors of this added value.
SmallVector<Value*, 8> Factors;
FindSingleUseMultiplyFactors(BOp, Factors);
Modified: llvm/trunk/test/Transforms/Reassociate/basictest.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/Reassociate/basictest.ll?rev=92354&r1=92353&r2=92354&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/Reassociate/basictest.ll (original)
+++ llvm/trunk/test/Transforms/Reassociate/basictest.ll Thu Dec 31 02:33:49 2009
@@ -133,3 +133,14 @@
; CHECK-NEXT: %C = sub i32 %Z, %A
; CHECK-NEXT: ret i32 %C
}
+
+
+; PR5458
+define i32 @test9(i32 %X) {
+ %Y = mul i32 %X, 47
+ %Z = add i32 %Y, %Y
+ ret i32 %Z
+; CHECK: @test9
+; CHECK-NEXT: %Z = mul i32 %X, 94
+; CHECK-NEXT: ret i32 %Z
+}
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