diff options
author | Dan Gohman <gohman@apple.com> | 2010-03-09 23:46:50 +0000 |
---|---|---|
committer | Dan Gohman <gohman@apple.com> | 2010-03-09 23:46:50 +0000 |
commit | 4ecbca558f8ee558dd0e84e079f16528fd9768f2 (patch) | |
tree | c697d4a61b5d72c1a576cd7e5bcd4432b42eb674 | |
parent | 0d9d70f0130ca609a1f41e0d90b3952751c110ab (diff) | |
download | external_llvm-4ecbca558f8ee558dd0e84e079f16528fd9768f2.zip external_llvm-4ecbca558f8ee558dd0e84e079f16528fd9768f2.tar.gz external_llvm-4ecbca558f8ee558dd0e84e079f16528fd9768f2.tar.bz2 |
Avoid analyzing instructions in blocks not reachable from the entry block.
They are lots of trouble, and they don't matter. This fixes PR6559.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@98103 91177308-0d34-0410-b5e6-96231b3b80d8
-rw-r--r-- | lib/Analysis/ScalarEvolution.cpp | 11 | ||||
-rw-r--r-- | test/Analysis/ScalarEvolution/unreachable-code.ll | 13 |
2 files changed, 22 insertions, 2 deletions
diff --git a/lib/Analysis/ScalarEvolution.cpp b/lib/Analysis/ScalarEvolution.cpp index b979f33..15f072d 100644 --- a/lib/Analysis/ScalarEvolution.cpp +++ b/lib/Analysis/ScalarEvolution.cpp @@ -3101,9 +3101,16 @@ const SCEV *ScalarEvolution::createSCEV(Value *V) { return getUnknown(V); unsigned Opcode = Instruction::UserOp1; - if (Instruction *I = dyn_cast<Instruction>(V)) + if (Instruction *I = dyn_cast<Instruction>(V)) { Opcode = I->getOpcode(); - else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) + + // Don't attempt to analyze instructions in blocks that aren't + // reachable. Such instructions don't matter, and they aren't required + // to obey basic rules for definitions dominating uses which this + // analysis depends on. + if (!DT->isReachableFromEntry(I->getParent())) + return getUnknown(V); + } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) Opcode = CE->getOpcode(); else if (ConstantInt *CI = dyn_cast<ConstantInt>(V)) return getConstant(CI); diff --git a/test/Analysis/ScalarEvolution/unreachable-code.ll b/test/Analysis/ScalarEvolution/unreachable-code.ll new file mode 100644 index 0000000..51d9398 --- /dev/null +++ b/test/Analysis/ScalarEvolution/unreachable-code.ll @@ -0,0 +1,13 @@ +; RUN: opt < %s -analyze -scalar-evolution | FileCheck %s + +; CHECK: %t = add i64 %t, 1 +; CHECK: --> %t + +define void @foo() { +entry: + ret void + +dead: + %t = add i64 %t, 1 + ret void +} |