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Conservatively, clear optional flags, such as nsw, when performing

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reassociation. No testcase, because I wasn't able to create a testcase
which actually demonstrates a problem.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@124713 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Dan Gohman 2011-02-02 02:05:46 +00:00
parent 46985a1440
commit 5195b71941
1 changed files with 15 additions and 0 deletions
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15
lib/Transforms/InstCombine/InstructionCombining.cpp
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@ -157,6 +157,9 @@ bool InstCombiner::SimplifyAssociativeOrCommutative(BinaryOperator &I) {
// It simplifies to V. Form "A op V". // It simplifies to V. Form "A op V".
I.setOperand(0, A); I.setOperand(0, A);
I.setOperand(1, V); I.setOperand(1, V);
// Conservatively clear the optional flags, since they may not be
// preserved by the reassociation.
I.clearSubclassOptionalData();
Changed = true; Changed = true;
++NumReassoc; ++NumReassoc;
continue; continue;
@ -174,6 +177,9 @@ bool InstCombiner::SimplifyAssociativeOrCommutative(BinaryOperator &I) {
// It simplifies to V. Form "V op C". // It simplifies to V. Form "V op C".
I.setOperand(0, V); I.setOperand(0, V);
I.setOperand(1, C); I.setOperand(1, C);
// Conservatively clear the optional flags, since they may not be
// preserved by the reassociation.
I.clearSubclassOptionalData();
Changed = true; Changed = true;
++NumReassoc; ++NumReassoc;
continue; continue;
@ -193,6 +199,9 @@ bool InstCombiner::SimplifyAssociativeOrCommutative(BinaryOperator &I) {
// It simplifies to V. Form "V op B". // It simplifies to V. Form "V op B".
I.setOperand(0, V); I.setOperand(0, V);
I.setOperand(1, B); I.setOperand(1, B);
// Conservatively clear the optional flags, since they may not be
// preserved by the reassociation.
I.clearSubclassOptionalData();
Changed = true; Changed = true;
++NumReassoc; ++NumReassoc;
continue; continue;
@ -210,6 +219,9 @@ bool InstCombiner::SimplifyAssociativeOrCommutative(BinaryOperator &I) {
// It simplifies to V. Form "B op V". // It simplifies to V. Form "B op V".
I.setOperand(0, B); I.setOperand(0, B);
I.setOperand(1, V); I.setOperand(1, V);
// Conservatively clear the optional flags, since they may not be
// preserved by the reassociation.
I.clearSubclassOptionalData();
Changed = true; Changed = true;
++NumReassoc; ++NumReassoc;
continue; continue;
@ -234,6 +246,9 @@ bool InstCombiner::SimplifyAssociativeOrCommutative(BinaryOperator &I) {
Worklist.Add(New); Worklist.Add(New);
I.setOperand(0, New); I.setOperand(0, New);
I.setOperand(1, Folded); I.setOperand(1, Folded);
// Conservatively clear the optional flags, since they may not be
// preserved by the reassociation.
I.clearSubclassOptionalData();
Changed = true; Changed = true;
continue; continue;
} }