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[Attributor][FIX] Ensure h2s doesn't trigger on escaped pointers

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We do not yet perform h2s because we know something is free'ed but we do
it because we know the pointer does not escape. Storing the pointer
allows it to escape so we have to prevent that.

llvm-svn: 374699
This commit is contained in:
Johannes Doerfert 2019-10-13 04:14:15 +00:00
parent 7b069a879a
commit 807d9bd946
2 changed files with 70 additions and 47 deletions
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10
lib/Transforms/IPO/Attributor.cpp
View File

@ -3569,8 +3569,16 @@ ChangeStatus AAHeapToStackImpl::updateImpl(Attributor &A) {
auto *UserI = U->getUser();
if (isa<LoadInst>(UserI) || isa<StoreInst>(UserI))
if (isa<LoadInst>(UserI))
continue;
if (auto *SI = dyn_cast<StoreInst>(UserI)) {
if (SI->getValueOperand() == U->get()) {
LLVM_DEBUG(dbgs() << "[H2S] escaping store to memory: " << *UserI << "\n");
return false;
}
// A store into the malloc'ed memory is fine.
continue;
}
// NOTE: Right now, if a function that has malloc pointer as an argument
// frees memory, we assume that the malloc pointer is freed.

107
test/Transforms/FunctionAttrs/heap_to_stack.ll
View File

@ -215,60 +215,46 @@ define void @test11() {
; TEST 12
define i32 @irreducible_cfg(i32 %0) {
%2 = alloca i32, align 4
%3 = alloca i32*, align 8
%4 = alloca i32, align 4
store i32 %0, i32* %2, align 4
%5 = call noalias i8* @malloc(i64 4) #2
; CHECK: alloca i8, i64 4
; CHECK-NEXT: %6 = bitcast
%6 = bitcast i8* %5 to i32*
store i32* %6, i32** %3, align 8
%7 = load i32*, i32** %3, align 8
store i32 10, i32* %7, align 4
%8 = load i32, i32* %2, align 4
%9 = icmp eq i32 %8, 1
br i1 %9, label %10, label %13
; CHECK-NEXT: %3 = bitcast
%2 = call noalias i8* @malloc(i64 4)
%3 = bitcast i8* %2 to i32*
store i32 10, i32* %3, align 4
%4 = icmp eq i32 %0, 1
br i1 %4, label %5, label %7
10: ; preds = %1
%11 = load i32, i32* %2, align 4
%12 = add nsw i32 %11, 5
store i32 %12, i32* %2, align 4
br label %20
5: ; preds = %1
%6 = add nsw i32 %0, 5
br label %13
13: ; preds = %1
store i32 1, i32* %2, align 4
br label %14
7: ; preds = %1
br label %8
14: ; preds = %20, %13
%15 = load i32*, i32** %3, align 8
%16 = load i32, i32* %15, align 4
%17 = add nsw i32 %16, -1
store i32 %17, i32* %15, align 4
%18 = icmp ne i32 %16, 0
br i1 %18, label %19, label %23
8: ; preds = %13, %7
%.0 = phi i32 [ %14, %13 ], [ 1, %7 ]
%9 = load i32, i32* %3, align 4
%10 = add nsw i32 %9, -1
store i32 %10, i32* %3, align 4
%11 = icmp ne i32 %9, 0
br i1 %11, label %12, label %15
19: ; preds = %14
br label %20
12: ; preds = %8
br label %13
20: ; preds = %19, %10
%21 = load i32, i32* %2, align 4
%22 = add nsw i32 %21, 1
store i32 %22, i32* %2, align 4
br label %14
13: ; preds = %12, %5
%.1 = phi i32 [ %6, %5 ], [ %.0, %12 ]
%14 = add nsw i32 %.1, 1
br label %8
23: ; preds = %14
%24 = load i32*, i32** %3, align 8
%25 = load i32, i32* %24, align 4
store i32 %25, i32* %4, align 4
%26 = load i32*, i32** %3, align 8
%27 = bitcast i32* %26 to i8*
call void @free(i8* %27) #2
%28 = load i32*, i32** %3, align 8
%29 = load i32, i32* %28, align 4
ret i32 %29
15: ; preds = %8
%16 = load i32, i32* %3, align 4
%17 = bitcast i32* %3 to i8*
call void @free(i8* %17)
%18 = load i32, i32* %3, align 4
ret i32 %18
}
define i32 @malloc_in_loop(i32 %0) {
%2 = alloca i32, align 4
%3 = alloca i32*, align 8
@ -286,7 +272,7 @@ define i32 @malloc_in_loop(i32 %0) {
%9 = call noalias i8* @malloc(i64 4)
; CHECK: alloca i8, i64 4
%10 = bitcast i8* %9 to i32*
store i32* %10, i32** %3, align 8
store i32 1, i32* %10, align 8
br label %4
11: ; preds = %4
@ -318,6 +304,35 @@ define void @test14() {
}
define void @test15(i64 %S) {
; CHECK: %1 = tail call noalias i8* @malloc(i64 %S)
%1 = tail call noalias i8* @malloc(i64 %S)
; CHECK-NEXT: @no_sync_func(i8* noalias %1)
tail call void @no_sync_func(i8* %1)
; CHECK-NEXT: @free(i8* noalias %1)
tail call void @free(i8* %1)
ret void
}
define void @test16a(i8 %v, i8** %P) {
; CHECK: %1 = alloca
%1 = tail call noalias i8* @malloc(i64 4)
; CHECK-NEXT: store i8 %v, i8* %1
store i8 %v, i8* %1
; CHECK-NEXT: @no_sync_func(i8* noalias nocapture %1)
tail call void @no_sync_func(i8* %1)
; CHECK-NOT: @free(i8* %1)
tail call void @free(i8* %1)
ret void
}
define void @test16b(i8 %v, i8** %P) {
; CHECK: %1 = tail call noalias i8* @malloc(i64 4)
%1 = tail call noalias i8* @malloc(i64 4)
; CHECK-NEXT: store i8* %1, i8** %P
store i8* %1, i8** %P
; CHECK-NEXT: @no_sync_func(i8* %1)
tail call void @no_sync_func(i8* %1)
; CHECK-NEXT: @free(i8* %1)
tail call void @free(i8* %1)
ret void
}