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[safestack] Sink unsafe address computation to each use.

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This is a fix for PR27844.
When replacing uses of unsafe allocas, emit the new location
immediately after each use. Without this, the pointer stays live from
the function entry to the last use, while it's usually cheaper to
recalculate.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@272969 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Evgeniy Stepanov
2016-06-16 22:34:04 +00:00
parent fd0154041b
commit f268616d77
6 changed files with 97 additions and 20 deletions
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test/Transforms/SafeStack/array-aligned.ll
+3 -4
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@@ -13,16 +13,15 @@ entry:
; CHECK: store i8* %[[USST]], i8** @__safestack_unsafe_stack_ptr
; CHECK: %[[AADDR:.*]] = alloca i8*, align 8
%a.addr = alloca i8*, align 8
; CHECK: %[[BUFPTR:.*]] = getelementptr i8, i8* %[[USP]], i32 -16
; CHECK: %[[BUFPTR2:.*]] = bitcast i8* %[[BUFPTR]] to [16 x i8]*
%buf = alloca [16 x i8], align 16
; CHECK: %[[AADDR:.*]] = alloca i8*, align 8
; CHECK: store i8* {{.*}}, i8** %[[AADDR]], align 8
store i8* %a, i8** %a.addr, align 8
; CHECK: %[[BUFPTR:.*]] = getelementptr i8, i8* %[[USP]], i32 -16
; CHECK: %[[BUFPTR2:.*]] = bitcast i8* %[[BUFPTR]] to [16 x i8]*
; CHECK: %[[GEP:.*]] = getelementptr inbounds [16 x i8], [16 x i8]* %[[BUFPTR2]], i32 0, i32 0
%gep = getelementptr inbounds [16 x i8], [16 x i8]* %buf, i32 0, i32 0
test/Transforms/SafeStack/array.ll
+3 -4
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@@ -17,16 +17,15 @@ entry:
; CHECK: store i8* %[[USST]], i8** @__safestack_unsafe_stack_ptr
; CHECK: %[[AADDR:.*]] = alloca i8*, align 8
%a.addr = alloca i8*, align 8
; CHECK: %[[BUFPTR:.*]] = getelementptr i8, i8* %[[USP]], i32 -4
; CHECK: %[[BUFPTR2:.*]] = bitcast i8* %[[BUFPTR]] to [4 x i8]*
%buf = alloca [4 x i8], align 1
; CHECK: %[[AADDR:.*]] = alloca i8*, align 8
; CHECK: store i8* {{.*}}, i8** %[[AADDR]], align 8
store i8* %a, i8** %a.addr, align 8
; CHECK: %[[BUFPTR:.*]] = getelementptr i8, i8* %[[USP]], i32 -4
; CHECK: %[[BUFPTR2:.*]] = bitcast i8* %[[BUFPTR]] to [4 x i8]*
; CHECK: %[[GEP:.*]] = getelementptr inbounds [4 x i8], [4 x i8]* %[[BUFPTR2]], i32 0, i32 0
%gep = getelementptr inbounds [4 x i8], [4 x i8]* %buf, i32 0, i32 0
test/Transforms/SafeStack/phi.ll
+35
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@@ -0,0 +1,35 @@
; RUN: opt -safe-stack -S -mtriple=i386-pc-linux-gnu < %s -o - | FileCheck %s
; RUN: opt -safe-stack -S -mtriple=x86_64-pc-linux-gnu < %s -o - | FileCheck %s
define void @f(i1 %d1, i1 %d2) safestack {
entry:
; CHECK-LABEL: define void @f(
; CHECK: %[[USP:.*]] = load i8*, i8** @__safestack_unsafe_stack_ptr
; CHECK-NEXT: getelementptr i8, i8* %[[USP]], i32 -16
; CHECK: br i1 %d1, label %[[BB0:.*]], label %[[BB1:.*]]
%a = alloca i32, align 8
%b = alloca i32, align 8
br i1 %d1, label %bb0, label %bb1
bb0:
; CHECK: [[BB0]]:
; CHECK: %[[Ai8:.*]] = getelementptr i8, i8* %unsafe_stack_ptr, i32
; CHECK: %[[AUNSAFE:.*]] = bitcast i8* %[[Ai8]] to i32*
; CHECK: br i1
br i1 %d2, label %bb2, label %bb2
bb1:
; CHECK: [[BB1]]:
; CHECK: %[[Bi8:.*]] = getelementptr i8, i8* %unsafe_stack_ptr, i32
; CHECK: %[[BUNSAFE:.*]] = bitcast i8* %[[Bi8]] to i32*
; CHECK: br label
br label %bb2
bb2:
; CHECK: phi i32* [ %[[AUNSAFE]], %[[BB0]] ], [ %[[AUNSAFE]], %[[BB0]] ], [ %[[BUNSAFE]], %[[BB1]] ]
%c = phi i32* [ %a, %bb0 ], [ %a, %bb0 ], [ %b, %bb1 ]
call void @capture(i32* %c)
ret void
}
declare void @capture(i32*)
test/Transforms/SafeStack/sink-to-use.ll
+22
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@@ -0,0 +1,22 @@
; Test that unsafe alloca address calculation is done immediately before each use.
; RUN: opt -safe-stack -S -mtriple=x86_64-pc-linux-gnu < %s -o - | FileCheck %s
; RUN: opt -safe-stack -S -mtriple=i386-pc-linux-gnu < %s -o - | FileCheck %s
define void @f() safestack {
entry:
%x0 = alloca i32, align 4
%x1 = alloca i32, align 4
; CHECK: %[[A:.*]] = getelementptr i8, i8* %{{.*}}, i32 -4
; CHECK: %[[X0:.*]] = bitcast i8* %[[A]] to i32*
; CHECK: call void @use(i32* %[[X0]])
call void @use(i32* %x0)
; CHECK: %[[B:.*]] = getelementptr i8, i8* %{{.*}}, i32 -8
; CHECK: %[[X1:.*]] = bitcast i8* %[[B]] to i32*
; CHECK: call void @use(i32* %[[X1]])
call void @use(i32* %x1)
ret void
}
declare void @use(i32*)
test/Transforms/SafeStack/struct.ll
+3 -4
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@@ -15,16 +15,15 @@ entry:
; CHECK: store i8* %[[USST]], i8** @__safestack_unsafe_stack_ptr
; CHECK: %[[AADDR:.*]] = alloca i8*, align 8
%a.addr = alloca i8*, align 8
; CHECK: %[[BUFPTR:.*]] = getelementptr i8, i8* %[[USP]], i32 -16
; CHECK: %[[BUFPTR2:.*]] = bitcast i8* %[[BUFPTR]] to %struct.foo*
%buf = alloca %struct.foo, align 1
; CHECK: %[[AADDR:.*]] = alloca i8*, align 8
; CHECK: store i8* {{.*}}, i8** %[[AADDR]], align 8
store i8* %a, i8** %a.addr, align 8
; CHECK: %[[BUFPTR:.*]] = getelementptr i8, i8* %[[USP]], i32 -16
; CHECK: %[[BUFPTR2:.*]] = bitcast i8* %[[BUFPTR]] to %struct.foo*
; CHECK: %[[GEP:.*]] = getelementptr inbounds %struct.foo, %struct.foo* %[[BUFPTR2]], i32 0, i32 0, i32 0
%gep = getelementptr inbounds %struct.foo, %struct.foo* %buf, i32 0, i32 0, i32 0