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[safestack] Fix assertion failure in stack coloring.

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This is a fix for PR30318.

Clang may generate IR where an alloca is already live when entering a
BB with lifetime.start. In this case, conservatively extend the
alloca lifetime all the way back to the block entry.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@281784 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Evgeniy Stepanov 2016-09-16 22:04:10 +00:00
parent 005bfb8238
commit df9dcaf1ee
2 changed files with 45 additions and 4 deletions
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10
lib/CodeGen/SafeStackColoring.cpp
View File

@ -214,10 +214,12 @@ void StackColoring::calculateLiveIntervals() {
unsigned AllocaNo = It.second.AllocaNo;
if (IsStart) {
assert(!Started.test(AllocaNo));
Started.set(AllocaNo);
Ended.reset(AllocaNo);
Start[AllocaNo] = InstNo;
assert(!Started.test(AllocaNo) || Start[AllocaNo] == BBStart);
if (!Started.test(AllocaNo)) {
Started.set(AllocaNo);
Ended.reset(AllocaNo);
Start[AllocaNo] = InstNo;
}
} else {
assert(!Ended.test(AllocaNo));
if (Started.test(AllocaNo)) {

39
test/Transforms/SafeStack/coloring2.ll
View File

@ -474,6 +474,45 @@ entry:
ret i32 %z3
}
define void @end_loop() safestack {
; CHECK-LABEL: define void @end_loop()
entry:
; CHECK: %[[USP:.*]] = load i8*, i8** @__safestack_unsafe_stack_ptr
; CHECK-NEXT: getelementptr i8, i8* %[[USP]], i32 -16
%x = alloca i8, align 4
call void @llvm.lifetime.start(i64 4, i8* %x) nounwind
br label %l2
l2:
call void @capture8(i8* %x)
call void @llvm.lifetime.end(i64 4, i8* %x) nounwind
br label %l2
}
; Check that @x and @y get distinct stack slots => @x lifetime does not break
; when control re-enters l2.
define void @start_loop() safestack {
; CHECK-LABEL: define void @start_loop()
entry:
; CHECK: %[[USP:.*]] = load i8*, i8** @__safestack_unsafe_stack_ptr
; CHECK-NEXT: getelementptr i8, i8* %[[USP]], i32 -16
%x = alloca i8, align 4
%y = alloca i8, align 4
call void @llvm.lifetime.start(i64 4, i8* %x) nounwind
br label %l2
l2:
; CHECK: getelementptr i8, i8* %[[USP]], i32 -8
call void @llvm.lifetime.start(i64 4, i8* %y) nounwind
call void @capture8(i8* %y)
call void @llvm.lifetime.end(i64 4, i8* %y) nounwind
; CHECK: getelementptr i8, i8* %[[USP]], i32 -4
call void @llvm.lifetime.start(i64 4, i8* %x) nounwind
call void @capture8(i8* %x)
br label %l2
}
declare void @llvm.lifetime.start(i64, i8* nocapture)
declare void @llvm.lifetime.end(i64, i8* nocapture)
declare void @capture8(i8*)