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Fix a use of an invalidated iterator in the case where there are multiple 

adjacent uses of a dead basic block from the same user. This fixes PR5596.

llvm-svn: 89658
This commit is contained in:
Dan Gohman 2009-11-23 16:13:39 +00:00
parent a6602e9e2a
commit 1f522d98f8
2 changed files with 35 additions and 1 deletions
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6
llvm/lib/Transforms/Scalar/SCCP.cpp
View File

@ -1871,8 +1871,12 @@ bool IPSCCP::runOnModule(Module &M) {
BasicBlock *DeadBB = BlocksToErase[i];
for (Value::use_iterator UI = DeadBB->use_begin(), UE = DeadBB->use_end();
UI != UE; ) {
// Grab the user and then increment the iterator early, as the user
// will be deleted. Step past all adjacent uses from the same user.
Instruction *I = dyn_cast<Instruction>(*UI);
do { ++UI; } while (UI != UE && *UI == I);
// Ignore blockaddress users; BasicBlock's dtor will handle them.
Instruction *I = dyn_cast<Instruction>(*UI++);
if (!I) continue;
bool Folded = ConstantFoldTerminator(I->getParent());

30
llvm/test/Transforms/IPConstantProp/user-with-multiple-uses.ll Normal file
View File

@ -0,0 +1,30 @@
; RUN: opt < %s -S -ipsccp | FileCheck %s
; PR5596
; IPSCCP should propagate the 0 argument, eliminate the switch, and propagate
; the result.
; CHECK: define i32 @main() noreturn nounwind {
; CHECK-NEXT: entry:
; CHECK-NEXT: %call2 = tail call i32 @wwrite(i64 0) nounwind
; CHECK-NEXT: ret i32 123
define i32 @main() noreturn nounwind {
entry:
%call2 = tail call i32 @wwrite(i64 0) nounwind
ret i32 %call2
}
define internal i32 @wwrite(i64 %i) nounwind readnone {
entry:
switch i64 %i, label %sw.default [
i64 3, label %return
i64 10, label %return
]
sw.default:
ret i32 123
return:
ret i32 0
}