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

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

2 files changed, 76 insertions, 53 deletions

diff --git a/llvm/lib/Transforms/IPO/Attributor.cpp b/llvm/lib/Transforms/IPO/Attributor.cpp
index 6db3f40b05f..ef6c82c00c8 100644
--- a/llvm/lib/Transforms/IPO/Attributor.cpp
+++ b/llvm/lib/Transforms/IPO/Attributor.cpp
@@ -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.
diff --git a/llvm/test/Transforms/FunctionAttrs/heap_to_stack.ll b/llvm/test/Transforms/FunctionAttrs/heap_to_stack.ll
index 542b233770c..876760a8051 100644
--- a/llvm/test/Transforms/FunctionAttrs/heap_to_stack.ll
+++ b/llvm/test/Transforms/FunctionAttrs/heap_to_stack.ll
@@ -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
-
-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
+  ; 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
+
+5:                                                ; preds = %1
+  %6 = add nsw i32 %0, 5
+  br label %13
+
+7:                                                ; preds = %1
+  br label %8
+
+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
+
+12:                                               ; preds = %8
+  br label %13
+
+13:                                               ; preds = %12, %5
+  %.1 = phi i32 [ %6, %5 ], [ %.0, %12 ]
+  %14 = add nsw i32 %.1, 1
+  br label %8
+
+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
 }