[PATCH][X86_64/MC] Towards usable Win64 exception handling
Kai Nacke
kai.nacke at redstar.de
Sat May 18 05:49:50 PDT 2013
Hi!
On 17.05.2013 22:00, Rafael Espíndola wrote:
> needs a testcase.
I realized that the main test case is currently marked as XFAIL because
of a wrong offset for unwind code SET_FP. I also fixed this, re-enabled
the test case and added a check for the changed relocation type.
Every aspect of this patch should now be covered by a test.
Regards
Kai
On 17.05.2013 16:27, Kai Nacke wrote:
> Hi!
>
> This patch fixes a couple of problems in the Win64 EH code.
>
> - The emitted EH handler is now the personality function specified in
> the IR instead of the hard coded _GCC_specific_handler
> (_GCC_specific_handler is not called from SEH code - it's
> __gcc_personality_seh0. Specify this as personality function if you like
> to try the GCC code.)
>
> - The Dwarf EH code ("gcc_except_table") is no longer emitted into a
> separate section but into the UNWIND_INFO structure as language specific
> handler data. A pointer to this data is passed in field
> DISPATCHER_CONTEXT->HandlerData to the personality function.
>
> - All relocations now use the VK_COFF_IMGREL32 modifier. This is
> required by the COFF specification and keeps the MS LINK tool happy. The
> linker flag /LARGEADDRESSAWARE:NO is no longer required.
>
> - Begin and end address of a function are now expressed as offsets from
> the function symbol instead of emitting the temporary labels. The latter
> approach didn't work with the VK_COFF_IMGREL32 modifier. Nice side
> effect is that llvm-objdump now displays the function symbol, too.
>
> Using this patch and a modified version of the patch to create the
> unwinding code from Charles Davis I am able to raise an exception
> via RaiseException and get the personality function called. :-)
>
> Please review. (BTW: This patch supersedes my mail "MCWin64EH:
> reloctions must be IMGREL32")
>
> Regards
> Kai
>
>
> _______________________________________________
> llvm-commits mailing list
> llvm-commits at cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits
>
-------------- next part --------------
diff --git a/lib/CodeGen/AsmPrinter/Win64Exception.cpp b/lib/CodeGen/AsmPrinter/Win64Exception.cpp
index 1561012..99d53b9 100644
--- a/lib/CodeGen/AsmPrinter/Win64Exception.cpp
+++ b/lib/CodeGen/AsmPrinter/Win64Exception.cpp
@@ -78,9 +78,9 @@ void Win64Exception::BeginFunction(const MachineFunction *MF) {
if (!shouldEmitPersonality)
return;
- MCSymbol *GCCHandlerSym =
- Asm->GetExternalSymbolSymbol("_GCC_specific_handler");
- Asm->OutStreamer.EmitWin64EHHandler(GCCHandlerSym, true, true);
+ const MCSymbol *PersHandlerSym = TLOF.getCFIPersonalitySymbol(Per, Asm->Mang,
+ MMI);
+ Asm->OutStreamer.EmitWin64EHHandler(PersHandlerSym, true, true);
Asm->OutStreamer.EmitLabel(Asm->GetTempSymbol("eh_func_begin",
Asm->getFunctionNumber()));
@@ -99,14 +99,8 @@ void Win64Exception::EndFunction() {
MMI->TidyLandingPads();
if (shouldEmitPersonality) {
- const TargetLoweringObjectFile &TLOF = Asm->getObjFileLowering();
- const Function *Per = MMI->getPersonalities()[MMI->getPersonalityIndex()];
- const MCSymbol *Sym = TLOF.getCFIPersonalitySymbol(Per, Asm->Mang, MMI);
-
Asm->OutStreamer.PushSection();
Asm->OutStreamer.EmitWin64EHHandlerData();
- Asm->OutStreamer.EmitValue(MCSymbolRefExpr::Create(Sym, Asm->OutContext),
- 4);
EmitExceptionTable();
Asm->OutStreamer.PopSection();
}
diff --git a/lib/MC/MCObjectFileInfo.cpp b/lib/MC/MCObjectFileInfo.cpp
index 96b62f1..1be20c3 100644
--- a/lib/MC/MCObjectFileInfo.cpp
+++ b/lib/MC/MCObjectFileInfo.cpp
@@ -547,11 +547,16 @@ void MCObjectFileInfo::InitCOFFMCObjectFileInfo(Triple T) {
// though it contains relocatable pointers. In PIC mode, this is probably a
// big runtime hit for C++ apps. Either the contents of the LSDA need to be
// adjusted or this should be a data section.
- LSDASection =
- Ctx->getCOFFSection(".gcc_except_table",
- COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
- COFF::IMAGE_SCN_MEM_READ,
- SectionKind::getReadOnly());
+ if (T.getOS() == Triple::Win32) {
+ // On Windows with SEH, the LSDA is emitted into the .xdata section
+ LSDASection = 0;
+ } else {
+ LSDASection =
+ Ctx->getCOFFSection(".gcc_except_table",
+ COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
+ COFF::IMAGE_SCN_MEM_READ,
+ SectionKind::getReadOnly());
+ }
// Debug info.
DwarfAbbrevSection =
diff --git a/lib/MC/MCStreamer.cpp b/lib/MC/MCStreamer.cpp
index 8f1895e..6e0c5e5 100644
--- a/lib/MC/MCStreamer.cpp
+++ b/lib/MC/MCStreamer.cpp
@@ -472,7 +472,9 @@ void MCStreamer::EmitWin64EHSetFrame(unsigned Register, unsigned Offset) {
report_fatal_error("Frame register and offset already specified!");
if (Offset & 0x0F)
report_fatal_error("Misaligned frame pointer offset!");
- MCWin64EHInstruction Inst(Win64EH::UOP_SetFPReg, 0, Register, Offset);
+ MCSymbol *Label = getContext().CreateTempSymbol();
+ MCWin64EHInstruction Inst(Win64EH::UOP_SetFPReg, Label, Register, Offset);
+ EmitLabel(Label);
CurFrame->LastFrameInst = CurFrame->Instructions.size();
CurFrame->Instructions.push_back(Inst);
}
diff --git a/lib/MC/MCWin64EH.cpp b/lib/MC/MCWin64EH.cpp
index c5b637c..c3d568b 100644
--- a/lib/MC/MCWin64EH.cpp
+++ b/lib/MC/MCWin64EH.cpp
@@ -64,7 +64,7 @@ static void EmitAbsDifference(MCStreamer &streamer, MCSymbol *lhs,
static void EmitUnwindCode(MCStreamer &streamer, MCSymbol *begin,
MCWin64EHInstruction &inst) {
- uint8_t b1, b2;
+ uint8_t b2;
uint16_t w;
b2 = (inst.getOperation() & 0x0F);
switch (inst.getOperation()) {
@@ -93,8 +93,7 @@ static void EmitUnwindCode(MCStreamer &streamer, MCSymbol *begin,
streamer.EmitIntValue(b2, 1);
break;
case Win64EH::UOP_SetFPReg:
- b1 = inst.getOffset() & 0xF0;
- streamer.EmitIntValue(b1, 1);
+ EmitAbsDifference(streamer, inst.getLabel(), begin);
streamer.EmitIntValue(b2, 1);
break;
case Win64EH::UOP_SaveNonVol:
@@ -129,14 +128,29 @@ static void EmitUnwindCode(MCStreamer &streamer, MCSymbol *begin,
}
}
+static void EmitSymbolRefWithOfs(MCStreamer &streamer,
+ const MCSymbol *Base,
+ const MCSymbol *Other) {
+ MCContext &Context = streamer.getContext();
+ const MCSymbolRefExpr *BaseRef = MCSymbolRefExpr::Create(Base, Context);
+ const MCSymbolRefExpr *OtherRef = MCSymbolRefExpr::Create(Other, Context);
+ const MCExpr *Ofs = MCBinaryExpr::CreateSub(OtherRef, BaseRef, Context);
+ const MCSymbolRefExpr *BaseRefRel = MCSymbolRefExpr::Create(Base,
+ MCSymbolRefExpr::VK_COFF_IMGREL32,
+ Context);
+ streamer.EmitValue(MCBinaryExpr::CreateAdd(BaseRefRel, Ofs, Context), 4);
+}
+
static void EmitRuntimeFunction(MCStreamer &streamer,
const MCWin64EHUnwindInfo *info) {
MCContext &context = streamer.getContext();
streamer.EmitValueToAlignment(4);
- streamer.EmitValue(MCSymbolRefExpr::Create(info->Begin, context), 4);
- streamer.EmitValue(MCSymbolRefExpr::Create(info->End, context), 4);
- streamer.EmitValue(MCSymbolRefExpr::Create(info->Symbol, context), 4);
+ EmitSymbolRefWithOfs(streamer, info->Function, info->Begin);
+ EmitSymbolRefWithOfs(streamer, info->Function, info->End);
+ streamer.EmitValue(MCSymbolRefExpr::Create(info->Symbol,
+ MCSymbolRefExpr::VK_COFF_IMGREL32,
+ context), 4);
}
static void EmitUnwindInfo(MCStreamer &streamer, MCWin64EHUnwindInfo *info) {
@@ -189,8 +203,9 @@ static void EmitUnwindInfo(MCStreamer &streamer, MCWin64EHUnwindInfo *info) {
EmitRuntimeFunction(streamer, info->ChainedParent);
else if (flags &
((Win64EH::UNW_TerminateHandler|Win64EH::UNW_ExceptionHandler) << 3))
- streamer.EmitValue(MCSymbolRefExpr::Create(info->ExceptionHandler, context),
- 4);
+ streamer.EmitValue(MCSymbolRefExpr::Create(info->ExceptionHandler,
+ MCSymbolRefExpr::VK_COFF_IMGREL32,
+ context), 4);
else if (numCodes < 2) {
// The minimum size of an UNWIND_INFO struct is 8 bytes. If we're not
// a chained unwind info, if there is no handler, and if there are fewer
diff --git a/test/MC/COFF/seh.s b/test/MC/COFF/seh.s
index bef425e..72d42f4 100644
--- a/test/MC/COFF/seh.s
+++ b/test/MC/COFF/seh.s
@@ -1,8 +1,6 @@
// This test checks that the SEH directives emit the correct unwind data.
-// TODO: Expected fail because SET_FPREG has a wrong offset.
-// XFAIL: *
-// RUN: llvm-mc -triple x86_64-pc-win32 -filetype=obj %s | llvm-readobj -s -u | FileCheck %s
+// RUN: llvm-mc -triple x86_64-pc-win32 -filetype=obj %s | llvm-readobj -s -u -r | FileCheck %s
// CHECK: Sections [
// CHECK: Section {
@@ -36,6 +34,27 @@
// CHECK-NEXT: }
// CHECK-NEXT: ]
+// CHECK-NEXT: Relocations [
+// CHECK-NEXT: Section (2) .xdata {
+// CHECK-NEXT: 0x14 IMAGE_REL_AMD64_ADDR32NB __C_specific_handler
+// CHECK-NEXT: 0x20 IMAGE_REL_AMD64_ADDR32NB func
+// CHECK-NEXT: 0x24 IMAGE_REL_AMD64_ADDR32NB func
+// CHECK-NEXT: 0x28 IMAGE_REL_AMD64_ADDR32NB .xdata
+// CHECK-NEXT: }
+// CHECK-NEXT: Section (3) .pdata {
+// CHECK-NEXT: 0x0 IMAGE_REL_AMD64_ADDR32NB func
+// CHECK-NEXT: 0x4 IMAGE_REL_AMD64_ADDR32NB func
+// CHECK-NEXT: 0x8 IMAGE_REL_AMD64_ADDR32NB .xdata
+// CHECK-NEXT: 0xC IMAGE_REL_AMD64_ADDR32NB func
+// CHECK-NEXT: 0x10 IMAGE_REL_AMD64_ADDR32NB func
+// CHECK-NEXT: 0x14 IMAGE_REL_AMD64_ADDR32NB .xdata
+// CHECK-NEXT: 0x18 IMAGE_REL_AMD64_ADDR32NB smallFunc
+// CHECK-NEXT: 0x1C IMAGE_REL_AMD64_ADDR32NB smallFunc
+// CHECK-NEXT: 0x20 IMAGE_REL_AMD64_ADDR32NB .xdata
+// CHECK-NEXT: }
+// CHECK-NEXT: ]
+
+
// CHECK: UnwindInformation [
// CHECK-NEXT: RuntimeFunction {
// CHECK-NEXT: StartAddress: [[CodeSect1:[^ ]+]] [[BeginDisp1:(\+0x[A-F0-9]+)?]]
diff --git a/test/tools/llvm-objdump/win64-unwind-data.s b/test/tools/llvm-objdump/win64-unwind-data.s
index 1e4c742..f8463fb 100644
--- a/test/tools/llvm-objdump/win64-unwind-data.s
+++ b/test/tools/llvm-objdump/win64-unwind-data.s
@@ -3,8 +3,8 @@
// CHECK: Unwind info:
// CHECK: Function Table:
-// CHECK-NEXT: Start Address: .text
-// CHECK-NEXT: End Address: .text + 0x001b
+// CHECK-NEXT: Start Address: func
+// CHECK-NEXT: End Address: func + 0x001b
// CHECK-NEXT: Unwind Info Address: .xdata
// CHECK-NEXT: Version: 1
// CHECK-NEXT: Flags: 1 UNW_ExceptionHandler
@@ -13,15 +13,15 @@
// CHECK-NEXT: Frame register: RBX
// CHECK-NEXT: Frame offset: 0
// CHECK-NEXT: Unwind Codes:
-// CHECK-NEXT: 0x00: UOP_SetFPReg
+// CHECK-NEXT: 0x12: UOP_SetFPReg
// CHECK-NEXT: 0x0f: UOP_PushNonVol RBX
// CHECK-NEXT: 0x0e: UOP_SaveXMM128 XMM8 [0x0000]
// CHECK-NEXT: 0x09: UOP_SaveNonVol RSI [0x0010]
// CHECK-NEXT: 0x04: UOP_AllocSmall 24
// CHECK-NEXT: 0x00: UOP_PushMachFrame w/o error code
// CHECK: Function Table:
-// CHECK-NEXT: Start Address: .text + 0x0012
-// CHECK-NEXT: End Address: .text + 0x0012
+// CHECK-NEXT: Start Address: func + 0x0012
+// CHECK-NEXT: End Address: func + 0x0012
// CHECK-NEXT: Unwind Info Address: .xdata + 0x001c
// CHECK-NEXT: Version: 1
// CHECK-NEXT: Flags: 4 UNW_ChainInfo
@@ -29,8 +29,8 @@
// CHECK-NEXT: Number of Codes: 0
// CHECK-NEXT: No frame pointer used
// CHECK: Function Table:
-// CHECK-NEXT: Start Address: .text + 0x001b
-// CHECK-NEXT: End Address: .text + 0x001c
+// CHECK-NEXT: Start Address: smallFunc
+// CHECK-NEXT: End Address: smallFunc + 0x0001
// CHECK-NEXT: Unwind Info Address: .xdata + 0x002c
// CHECK-NEXT: Version: 1
// CHECK-NEXT: Flags: 0
@@ -38,8 +38,8 @@
// CHECK-NEXT: Number of Codes: 0
// CHECK-NEXT: No frame pointer used
// CHECK: Function Table:
-// CHECK-NEXT: Start Address: .text + 0x001c
-// CHECK-NEXT: End Address: .text + 0x0039
+// CHECK-NEXT: Start Address: allocFunc
+// CHECK-NEXT: End Address: allocFunc + 0x001d
// CHECK-NEXT: Unwind Info Address: .xdata + 0x0034
// CHECK-NEXT: Version: 1
// CHECK-NEXT: Flags: 0
@@ -90,9 +90,9 @@ smallFunc:
.seh_endproc
// Function with big stack allocation.
- .globl smallFunc
+ .globl allocFunc
.def allocFunc; .scl 2; .type 32; .endef
- .seh_proc smallFunc
+ .seh_proc allocFunc
allocFunc:
.seh_pushframe @code
subq $65520, %rsp
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