ssijaric created this revision.
ssijaric added reviewers: rnk, efriedma, mstorsjo, TomTan.
The following test case, compiled with -OO -target=x86_64-windows-win32,
returns an incorrect value. It returns 5, when it should return 9. The
problem is that the frame pointer that the first finally block receives is not
passed onto the second finally block, but is regenerated using the localaddr
intrinsic.
The test case is:
int
main() {
int Check = 0;
__try {
Check = 3;
} __finally {
__try {
Check += 2;
} __finally {
Check += 4;
}
}
return Check;
}
The code generated with "-O0 --target=x86_64-windows-win32" is:
main: # @main
.seh_proc main
# %bb.0: # %entry
subq $40, %rsp
.seh_stackalloc 40
.seh_endprologue
xorl %ecx, %ecx
.set .Lmain$frame_escape_0, 32 <==== Check is at %rsp of main + 32
movl $0, 36(%rsp)
movl $0, 32(%rsp)
movl $3, 32(%rsp)
movq %rsp, %rax
movq %rax, %rdx <==== main's %rsp is passed to fin$0
callq "?fin$0@0@main@@"
movl 32(%rsp), %eax
addq $40, %rsp
retq
?fin$0@0@main@@:
subq $56, %rsp
leaq .Lmain$frame_escape_0(%rdx), %r8
movq %rdx, 48(%rsp)
movb %cl, 47(%rsp)
movl (%r8), %r9d <==== Check is at %rsp of main + 32
addl $2, %r9d
movq %rsp, %rdx <==== %rsp of fin$0 is passed to fin$1, should
be %rsp of main
movl %eax, %ecx
callq "?fin$1@0@main@@"
"?fin$1@0@main@@": # @"?fin$1@0@main@@"
# %bb.0: # %entry
subq $16, %rsp
.seh_stackalloc 16
.seh_endprologue
leaq .Lmain$frame_escape_0(%rdx), %rax
movq %rdx, 8(%rsp)
movb %cl, 7(%rsp)
movl (%rax), %r8d
addl $4, %r8d
movl %r8d, (%rax)
addq $16, %rsp
retq
.seh_handlerdata
.text
With this change, we get the following:
"?fin$0@0@main@@": # @"?fin$0@0@main@@"
.seh_proc "?fin$0@0@main@@"
# %bb.0: # %entry
subq $56, %rsp
.seh_stackalloc 56
.seh_endprologue
xorl %eax, %eax
leaq .Lmain$frame_escape_0(%rdx), %r8
movq %rdx, 48(%rsp)
movb %cl, 47(%rsp)
movl (%r8), %r9d
addl $2, %r9d
movl %r9d, (%r8)
movl %eax, %ecx
callq "?fin$1@0@main@@" <==== %rsp of main is passed in %rdx onto
fin$1
nop
addq $56, %rsp
retq
The change assumes that no compiler generated filter function can directly
invoke a compiler generated finally function. I haven't been able to come up
with a test case where this occurs. Otherwise, the check for
IsOutlinedSEHHelper is insufficient. All SEH finally functions have two
parameters, the second being the frame pointer. This is not the case for
filter functions, as they differ on x86 vs x86_64.
Repository:
rC Clang
https://reviews.llvm.org/D56463
Files:
lib/CodeGen/CGException.cpp
test/CodeGen/exceptions-seh-nested-finally.c
Index: test/CodeGen/exceptions-seh-nested-finally.c
===================================================================
--- /dev/null
+++ test/CodeGen/exceptions-seh-nested-finally.c
@@ -0,0 +1,26 @@
+// RUN: %clang_cc1 %s -triple x86_64-pc-win32 -fms-extensions -emit-llvm -o - \
+// RUN: | FileCheck %s
+// RUN: %clang_cc1 %s -triple i686-pc-win32 -fms-extensions -emit-llvm -o - \
+// RUN: | FileCheck %s
+// RUN: %clang_cc1 %s -triple aarch64-windows -fms-extensions -emit-llvm -o - \
+// RUN: | FileCheck %s
+
+// Check that the first finally block passes the enclosing function's frame
+// pointer to the second finally block, instead of generating it via localaddr.
+
+// CHECK-LABEL: define internal void @"?fin$0@0@main@@"({{i8( zeroext)?}}
%abnormal_termination, i8* %frame_pointer)
+// CHECK: call void @"?fin$1@0@main@@"({{i8( zeroext)?}} 0, i8* %frame_pointer)
+int
+main() {
+ int Check = 0;
+ __try {
+ Check = 3;
+ } __finally {
+ __try {
+ Check += 2;
+ } __finally {
+ Check += 4;
+ }
+ }
+ return Check;
+}
Index: lib/CodeGen/CGException.cpp
===================================================================
--- lib/CodeGen/CGException.cpp
+++ lib/CodeGen/CGException.cpp
@@ -1627,8 +1627,15 @@
// Compute the two argument values.
QualType ArgTys[2] = {Context.UnsignedCharTy, Context.VoidPtrTy};
- llvm::Value *LocalAddrFn = CGM.getIntrinsic(llvm::Intrinsic::localaddress);
- llvm::Value *FP = CGF.Builder.CreateCall(LocalAddrFn);
+ llvm::Value *FP = nullptr;
+ // If CFG.IsOutlinedSEHHelper is true, then we are within a finally block.
+ if (CGF.IsOutlinedSEHHelper)
+ FP = &CGF.CurFn->arg_begin()[1];
+ else {
+ llvm::Value *LocalAddrFn =
CGM.getIntrinsic(llvm::Intrinsic::localaddress);
+ FP = CGF.Builder.CreateCall(LocalAddrFn);
+ }
+
llvm::Value *IsForEH =
llvm::ConstantInt::get(CGF.ConvertType(ArgTys[0]), F.isForEHCleanup());
Args.add(RValue::get(IsForEH), ArgTys[0]);
Index: test/CodeGen/exceptions-seh-nested-finally.c
===================================================================
--- /dev/null
+++ test/CodeGen/exceptions-seh-nested-finally.c
@@ -0,0 +1,26 @@
+// RUN: %clang_cc1 %s -triple x86_64-pc-win32 -fms-extensions -emit-llvm -o - \
+// RUN: | FileCheck %s
+// RUN: %clang_cc1 %s -triple i686-pc-win32 -fms-extensions -emit-llvm -o - \
+// RUN: | FileCheck %s
+// RUN: %clang_cc1 %s -triple aarch64-windows -fms-extensions -emit-llvm -o - \
+// RUN: | FileCheck %s
+
+// Check that the first finally block passes the enclosing function's frame
+// pointer to the second finally block, instead of generating it via localaddr.
+
+// CHECK-LABEL: define internal void @"?fin$0@0@main@@"({{i8( zeroext)?}} %abnormal_termination, i8* %frame_pointer)
+// CHECK: call void @"?fin$1@0@main@@"({{i8( zeroext)?}} 0, i8* %frame_pointer)
+int
+main() {
+ int Check = 0;
+ __try {
+ Check = 3;
+ } __finally {
+ __try {
+ Check += 2;
+ } __finally {
+ Check += 4;
+ }
+ }
+ return Check;
+}
Index: lib/CodeGen/CGException.cpp
===================================================================
--- lib/CodeGen/CGException.cpp
+++ lib/CodeGen/CGException.cpp
@@ -1627,8 +1627,15 @@
// Compute the two argument values.
QualType ArgTys[2] = {Context.UnsignedCharTy, Context.VoidPtrTy};
- llvm::Value *LocalAddrFn = CGM.getIntrinsic(llvm::Intrinsic::localaddress);
- llvm::Value *FP = CGF.Builder.CreateCall(LocalAddrFn);
+ llvm::Value *FP = nullptr;
+ // If CFG.IsOutlinedSEHHelper is true, then we are within a finally block.
+ if (CGF.IsOutlinedSEHHelper)
+ FP = &CGF.CurFn->arg_begin()[1];
+ else {
+ llvm::Value *LocalAddrFn = CGM.getIntrinsic(llvm::Intrinsic::localaddress);
+ FP = CGF.Builder.CreateCall(LocalAddrFn);
+ }
+
llvm::Value *IsForEH =
llvm::ConstantInt::get(CGF.ConvertType(ArgTys[0]), F.isForEHCleanup());
Args.add(RValue::get(IsForEH), ArgTys[0]);
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