[Attributor] Heap-To-Stack Conversion

D53362 gives a prototype heap-to-stack conversion pass. With addition of new attributes in the attributor, this can now be revisted and improved. This will place it in the Attributor to make it easier to use new attributes (eg. nofree, nosync, willreturn, etc.) and other attributor features.

Reviewers: jdoerfert, uenoku, hfinkel, efriedma

Subscribers: lebedev.ri, xbolva00, hiraditya, llvm-commits

Differential Revision: https://reviews.llvm.org/D65408

llvm-svn: 371942

1 files changed, 318 insertions, 0 deletions

diff --git a/llvm/test/Transforms/FunctionAttrs/heap_to_stack.ll b/llvm/test/Transforms/FunctionAttrs/heap_to_stack.ll
new file mode 100644
index 00000000000..26a778be841
--- /dev/null
+++ b/llvm/test/Transforms/FunctionAttrs/heap_to_stack.ll
@@ -0,0 +1,318 @@
+; RUN: opt -passes=attributor --attributor-disable=false -S < %s | FileCheck %s
+
+declare noalias i8* @malloc(i64)
+
+declare void @nocapture_func_frees_pointer(i8* nocapture)
+
+declare void @func_throws(...)
+
+declare void @sync_func(i8* %p)
+
+declare void @sync_will_return(i8* %p) willreturn
+
+declare void @no_sync_func(i8* nocapture %p) nofree nosync willreturn
+
+declare void @nofree_func(i8* nocapture %p) nofree  nosync willreturn
+
+declare void @foo(i32* %p)
+
+declare void @foo_nounw(i32* %p) nounwind nofree
+
+declare i32 @no_return_call() noreturn
+
+declare void @free(i8* nocapture)
+
+declare void @llvm.lifetime.start.p0i8(i64, i8* nocapture) nounwind
+
+; TEST 1 - negative, pointer freed in another function.
+
+define void @test1() {
+  %1 = tail call noalias i8* @malloc(i64 4)
+  ; CHECK: @malloc(i64 4)
+  ; CHECK-NEXT: @nocapture_func_frees_pointer(i8* noalias nocapture %1)
+  tail call void @nocapture_func_frees_pointer(i8* %1)
+  tail call void (...) @func_throws()
+  tail call void @free(i8* %1)
+  ret void
+}
+
+; TEST 2 - negative, call to a sync function.
+
+define void @test2() {
+  %1 = tail call noalias i8* @malloc(i64 4)
+  ; CHECK: @malloc(i64 4)
+  ; CHECK-NEXT: @sync_func(i8* %1)
+  tail call void @sync_func(i8* %1)
+  tail call void @free(i8* %1)
+  ret void
+}
+
+; TEST 3 - 1 malloc, 1 free
+
+define void @test3() {
+  %1 = tail call noalias i8* @malloc(i64 4)
+  ; CHECK: %1 = alloca i8, i64 4
+  ; 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
+}
+
+declare noalias i8* @calloc(i64, i64)
+
+define void @test0() {
+  %1 = tail call noalias i8* @calloc(i64 2, i64 4)
+  ; CHECK: %1 = alloca i8, i64 8
+  ; CHECK-NEXT: %calloc_bc = bitcast i8* %1 to i8*
+  ; CHECK-NEXT: call void @llvm.memset.p0i8.i64(i8* %calloc_bc, i8 0, i64 8, i1 false)
+  ; 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
+}
+
+; TEST 4 
+define void @test4() {
+  %1 = tail call noalias i8* @malloc(i64 4)
+  ; CHECK: %1 = alloca i8, i64 4
+  ; CHECK-NEXT: @nofree_func(i8* noalias nocapture %1)
+  tail call void @nofree_func(i8* %1)
+  ret void
+}
+
+; TEST 5 - not all exit paths have a call to free, but all uses of malloc
+; are in nofree functions and are not captured
+
+define void @test5(i32) {
+  %2 = tail call noalias i8* @malloc(i64 4)
+  ; CHECK: %2 = alloca i8, i64 4
+  ; CHECK-NEXT: icmp eq i32 %0, 0
+  %3 = icmp eq i32 %0, 0
+  br i1 %3, label %5, label %4
+
+4:                                                ; preds = %1
+  tail call void @nofree_func(i8* %2)
+  br label %6
+
+5:                                                ; preds = %1
+  tail call void @free(i8* %2)
+  ; CHECK-NOT: @free(i8* %2)
+  br label %6
+
+6:                                                ; preds = %5, %4
+  ret void
+}
+
+; TEST 6 - all exit paths have a call to free
+
+define void @test6(i32) {
+  %2 = tail call noalias i8* @malloc(i64 4)
+  ; CHECK: %2 = alloca i8, i64 4
+  ; CHECK-NEXT: icmp eq i32 %0, 0
+  %3 = icmp eq i32 %0, 0
+  br i1 %3, label %5, label %4
+
+4:                                                ; preds = %1
+  tail call void @nofree_func(i8* %2)
+  tail call void @free(i8* %2)
+  ; CHECK-NOT: @free(i8* %2)
+  br label %6
+
+5:                                                ; preds = %1
+  tail call void @free(i8* %2)
+  ; CHECK-NOT: @free(i8* %2)
+  br label %6
+
+6:                                                ; preds = %5, %4
+  ret void
+}
+
+; TEST 7 - free is dead.
+
+define void @test7() {
+  %1 = tail call noalias i8* @malloc(i64 4)
+  ; CHECK: alloca i8, i64 4
+  ; CHECK-NEXT: tail call i32 @no_return_call()
+  tail call i32 @no_return_call()
+  ; CHECK-NOT: @free(i8* %1)
+  tail call void @free(i8* %1)
+  ret void
+}
+
+; TEST 8 - Negative: bitcast pointer used in capture function
+
+define void @test8() {
+  %1 = tail call noalias i8* @malloc(i64 4)
+  ; CHECK: %1 = tail call noalias i8* @malloc(i64 4)
+  ; CHECK-NEXT: @no_sync_func(i8* nocapture %1)
+  tail call void @no_sync_func(i8* %1)
+  %2 = bitcast i8* %1 to i32*
+  store i32 10, i32* %2
+  %3 = load i32, i32* %2
+  tail call void @foo(i32* %2)
+  ; CHECK: @free(i8* %1)
+  tail call void @free(i8* %1)
+  ret void
+}
+
+; TEST 9 - FIXME: malloc should be converted.
+define void @test9() {
+  %1 = tail call noalias i8* @malloc(i64 4)
+  ; CHECK: %1 = tail call noalias i8* @malloc(i64 4)
+  ; CHECK-NEXT: @no_sync_func(i8* nocapture %1)
+  tail call void @no_sync_func(i8* %1)
+  %2 = bitcast i8* %1 to i32*
+  store i32 10, i32* %2
+  %3 = load i32, i32* %2
+  tail call void @foo_nounw(i32* %2)
+  ; CHECK: @free(i8* %1)
+  tail call void @free(i8* %1)
+  ret void
+}
+
+; TEST 10 - 1 malloc, 1 free
+
+define i32 @test10() {
+  %1 = tail call noalias i8* @malloc(i64 4)
+  ; CHECK: %1 = alloca i8, i64 4
+  ; CHECK-NEXT: @no_sync_func(i8* noalias nocapture %1)
+  tail call void @no_sync_func(i8* %1)
+  %2 = bitcast i8* %1 to i32*
+  store i32 10, i32* %2
+  %3 = load i32, i32* %2
+  ; CHECK-NOT: @free(i8* %1)
+  tail call void @free(i8* %1)
+  ret i32 %3
+}
+
+define i32 @test_lifetime() {
+  %1 = tail call noalias i8* @malloc(i64 4)
+  ; CHECK: %1 = alloca i8, i64 4
+  ; CHECK-NEXT: @no_sync_func(i8* noalias nocapture %1)
+  tail call void @no_sync_func(i8* %1)
+  call void @llvm.lifetime.start.p0i8(i64 4, i8* %1)
+  %2 = bitcast i8* %1 to i32*
+  store i32 10, i32* %2
+  %3 = load i32, i32* %2
+  ; CHECK-NOT: @free(i8* %1)
+  tail call void @free(i8* %1)
+  ret i32 %3
+}
+
+; TEST 11 
+; FIXME: should be ok
+
+define void @test11() {
+  %1 = tail call noalias i8* @malloc(i64 4)
+  ; CHECK: @malloc(i64 4)
+  ; CHECK-NEXT: @sync_will_return(i8* %1)
+  tail call void @sync_will_return(i8* %1)
+  tail call void @free(i8* %1)
+  ret void
+}
+
+; 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
+
+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
+
+13:                                               ; preds = %1
+  store i32 1, i32* %2, align 4
+  br label %14
+
+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
+
+19:                                               ; preds = %14
+  br label %20
+
+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
+
+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
+}
+
+define i32 @malloc_in_loop(i32 %0) {
+  %2 = alloca i32, align 4
+  %3 = alloca i32*, align 8
+  store i32 %0, i32* %2, align 4
+  br label %4
+
+4:                                                ; preds = %8, %1
+  %5 = load i32, i32* %2, align 4
+  %6 = add nsw i32 %5, -1
+  store i32 %6, i32* %2, align 4
+  %7 = icmp sgt i32 %6, 0
+  br i1 %7, label %8, label %11
+
+8:                                                ; preds = %4
+  %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
+  br label %4
+
+11:                                               ; preds = %4
+  ret i32 5
+}
+
+; Malloc/Calloc too large
+define i32 @test13() {
+  %1 = tail call noalias i8* @malloc(i64 256)
+  ; CHECK: %1 = tail call noalias i8* @malloc(i64 256)
+  ; CHECK-NEXT: @no_sync_func(i8* noalias %1)
+  tail call void @no_sync_func(i8* %1)
+  %2 = bitcast i8* %1 to i32*
+  store i32 10, i32* %2
+  %3 = load i32, i32* %2
+  tail call void @free(i8* %1)
+  ; CHECK: tail call void @free(i8* noalias %1)
+  ret i32 %3
+}
+
+define void @test14() {
+  %1 = tail call noalias i8* @calloc(i64 64, i64 4)
+  ; CHECK: %1 = tail call noalias i8* @calloc(i64 64, i64 4)
+  ; CHECK-NEXT: @no_sync_func(i8* noalias %1)
+  tail call void @no_sync_func(i8* %1)
+  tail call void @free(i8* %1)
+  ; CHECK: tail call void @free(i8* noalias %1)
+  ret void
+}