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authorDuncan Sands <baldrick@free.fr>2010-11-18 19:59:41 +0000
committerDuncan Sands <baldrick@free.fr>2010-11-18 19:59:41 +0000
commitd0c6f3dafd7c3e9137d4e6415014c94137fcd3fc (patch)
tree99b6f88540f7b3c4a552911c4020f9e8a42ab9eb /lib/Transforms/Scalar/LoopUnswitch.cpp
parent707120047e0107cb15dd4bbb31613df129b13c7a (diff)
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Factor code for testing whether replacing one value with another
preserves LCSSA form out of ScalarEvolution and into the LoopInfo class. Use it to check that SimplifyInstruction simplifications are not breaking LCSSA form. Fixes PR8622. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@119727 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'lib/Transforms/Scalar/LoopUnswitch.cpp')
-rw-r--r--lib/Transforms/Scalar/LoopUnswitch.cpp13
1 files changed, 7 insertions, 6 deletions
diff --git a/lib/Transforms/Scalar/LoopUnswitch.cpp b/lib/Transforms/Scalar/LoopUnswitch.cpp
index 009ee7b..2eaeb43 100644
--- a/lib/Transforms/Scalar/LoopUnswitch.cpp
+++ b/lib/Transforms/Scalar/LoopUnswitch.cpp
@@ -990,15 +990,16 @@ void LoopUnswitch::SimplifyCode(std::vector<Instruction*> &Worklist, Loop *L) {
++NumSimplify;
continue;
}
-
+
// See if instruction simplification can hack this up. This is common for
// things like "select false, X, Y" after unswitching made the condition be
// 'false'.
- if (Value *V = SimplifyInstruction(I, 0, DT)) {
- ReplaceUsesOfWith(I, V, Worklist, L, LPM);
- continue;
- }
-
+ if (Value *V = SimplifyInstruction(I, 0, DT))
+ if (LI->replacementPreservesLCSSAForm(I, V)) {
+ ReplaceUsesOfWith(I, V, Worklist, L, LPM);
+ continue;
+ }
+
// Special case hacks that appear commonly in unswitched code.
if (BranchInst *BI = dyn_cast<BranchInst>(I)) {
if (BI->isUnconditional()) {