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Fix alignment of unwind data.
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For alignment purposes, the instruction array will always have an even
number of entries, with the final entry potentially unused (in which
case the array will be one longer than indicated by the count of unwind
codes field).

Reviewed by Anton Korobeynikov, Charles Davis and Nico Rieck.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@190767 91177308-0d34-0410-b5e6-96231b3b80d8
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1 parent 7185bdd commit c29a720
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Showing 4 changed files with 238 additions and 7 deletions.
19 changes: 12 additions & 7 deletions lib/MC/MCWin64EH.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -159,11 +159,11 @@ static void EmitUnwindInfo(MCStreamer &streamer, MCWin64EHUnwindInfo *info) {

MCContext &context = streamer.getContext();
streamer.EmitValueToAlignment(4);
// Upper 3 bits are the version number (currently 1).
uint8_t flags = 0x01;
info->Symbol = context.CreateTempSymbol();
streamer.EmitLabel(info->Symbol);

// Upper 3 bits are the version number (currently 1).
uint8_t flags = 0x01;
if (info->ChainedParent)
flags |= Win64EH::UNW_ChainInfo << 3;
else {
Expand Down Expand Up @@ -199,21 +199,26 @@ static void EmitUnwindInfo(MCStreamer &streamer, MCWin64EHUnwindInfo *info) {
EmitUnwindCode(streamer, info->Begin, inst);
}

// For alignment purposes, the instruction array will always have an even
// number of entries, with the final entry potentially unused (in which case
// the array will be one longer than indicated by the count of unwind codes
// field).
if (numCodes & 1) {
streamer.EmitIntValue(0, 2);
}

if (flags & (Win64EH::UNW_ChainInfo << 3))
EmitRuntimeFunction(streamer, info->ChainedParent);
else if (flags &
((Win64EH::UNW_TerminateHandler|Win64EH::UNW_ExceptionHandler) << 3))
streamer.EmitValue(MCSymbolRefExpr::Create(info->ExceptionHandler,
MCSymbolRefExpr::VK_COFF_IMGREL32,
context), 4);
else if (numCodes < 2) {
else if (numCodes == 0) {
// 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
// than 2 slots used in the unwind code array, we have to pad to 8 bytes.
if (numCodes == 1)
streamer.EmitIntValue(0, 2);
else
streamer.EmitIntValue(0, 4);
streamer.EmitIntValue(0, 4);
}
}

Expand Down
65 changes: 65 additions & 0 deletions test/MC/COFF/seh-align1.s
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Original file line number Diff line number Diff line change
@@ -0,0 +1,65 @@
// This test checks the alignment and padding of the unwind info.

// RUN: llvm-mc -triple x86_64-pc-win32 -filetype=obj %s | llvm-readobj -s -sd -sr -u | FileCheck %s

// CHECK: Sections [
// CHECK: Section {
// CHECK: Name: .xdata
// CHECK: RawDataSize: 8
// CHECK: RelocationCount: 0
// CHECK: Characteristics [
// CHECK-NEXT: ALIGN_4BYTES
// CHECK-NEXT: CNT_INITIALIZED_DATA
// CHECK-NEXT: MEM_READ
// CHECK-NEXT: ]
// CHECK: Relocations [
// CHECK-NEXT: ]
// CHECK: SectionData (
// CHECK-NEXT: 0000: 01000000 00000000
// CHECK-NEXT: )
// CHECK-NEXT: }
// CHECK: Section {
// CHECK: Name: .pdata
// CHECK: RawDataSize: 12
// CHECK: RelocationCount: 3
// CHECK: Characteristics [
// CHECK-NEXT: IMAGE_SCN_ALIGN_4BYTES
// CHECK-NEXT: IMAGE_SCN_CNT_INITIALIZED_DATA
// CHECK-NEXT: IMAGE_SCN_MEM_READ
// CHECK-NEXT: ]
// CHECK: Relocations [
// CHECK-NEXT: [[BeginDisp:0x[A-F0-9]+]] IMAGE_REL_AMD64_ADDR32NB smallFunc
// CHECK-NEXT: [[EndDisp:0x[A-F0-9]+]] IMAGE_REL_AMD64_ADDR32NB smallFunc
// CHECK-NEXT: [[UnwindDisp:0x[A-F0-9]+]] IMAGE_REL_AMD64_ADDR32NB .xdata
// CHECK-NEXT: ]
// CHECK: SectionData (
// CHECK-NEXT: 0000: 00000000 01000000 00000000
// CHECK-NEXT: )
// CHECK-NEXT: }
// CHECK: UnwindInformation [
// CHECK-NEXT: RuntimeFunction {
// CHECK-NEXT: StartAddress: smallFunc {{(\+0x[A-F0-9]+ )?}}([[BeginDisp]])
// CHECK-NEXT: EndAddress: smallFunc {{(\+0x[A-F0-9]+ )?}}([[EndDisp]])
// CHECK-NEXT: UnwindInfoAddress: .xdata {{(\+0x[A-F0-9]+ )?}}([[UnwindDisp]])
// CHECK-NEXT: UnwindInfo {
// CHECK-NEXT: Version: 1
// CHECK-NEXT: Flags [
// CHECK-NEXT: ]
// CHECK-NEXT: PrologSize: 0
// CHECK-NEXT: FrameRegister: -
// CHECK-NEXT: FrameOffset: -
// CHECK-NEXT: UnwindCodeCount: 0
// CHECK-NEXT: UnwindCodes [
// CHECK-NEXT: ]
// CHECK-NEXT: }
// CHECK-NEXT: }
// CHECK-NEXT: ]

// Generate the minimal unwind info.
// It contains only the version set to 1. All other bytes are 0.
.globl smallFunc
.def smallFunc; .scl 2; .type 32; .endef
.seh_proc smallFunc
smallFunc:
ret
.seh_endproc
78 changes: 78 additions & 0 deletions test/MC/COFF/seh-align2.s
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Original file line number Diff line number Diff line change
@@ -0,0 +1,78 @@
// This test checks the alignment and padding of the unwind info.

// RUN: llvm-mc -triple x86_64-pc-win32 -filetype=obj %s | llvm-readobj -s -sd -sr -u | FileCheck %s

// CHECK: Sections [
// CHECK: Section {
// CHECK: Name: .xdata
// CHECK: RawDataSize: 16
// CHECK: RelocationCount: 1
// CHECK: Characteristics [
// CHECK-NEXT: ALIGN_4BYTES
// CHECK-NEXT: CNT_INITIALIZED_DATA
// CHECK-NEXT: MEM_READ
// CHECK-NEXT: ]
// CHECK: Relocations [
// CHECK-NEXT: [[HandlerDisp:0x[A-F0-9]+]] IMAGE_REL_AMD64_ADDR32NB __C_specific_handler
// CHECK-NEXT: ]
// CHECK: SectionData (
// CHECK-NEXT: 0000: 09000100 04220000 00000000 BEBAFECA
// CHECK-NEXT: )
// CHECK-NEXT: }
// CHECK-NEXT: Section {
// CHECK: Name: .pdata
// CHECK: RawDataSize: 12
// CHECK: RelocationCount: 3
// CHECK: Characteristics [
// CHECK-NEXT: IMAGE_SCN_ALIGN_4BYTES
// CHECK-NEXT: IMAGE_SCN_CNT_INITIALIZED_DATA
// CHECK-NEXT: IMAGE_SCN_MEM_READ
// CHECK-NEXT: ]
// CHECK: Relocations [
// CHECK-NEXT: [[BeginDisp:0x[A-F0-9]+]] IMAGE_REL_AMD64_ADDR32NB func
// CHECK-NEXT: [[EndDisp:0x[A-F0-9]+]] IMAGE_REL_AMD64_ADDR32NB func
// CHECK-NEXT: [[UnwindDisp:0x[A-F0-9]+]] IMAGE_REL_AMD64_ADDR32NB .xdata
// CHECK-NEXT: ]
// CHECK: SectionData (
// CHECK-NEXT: 0000: FCFFFFFF 05000000 00000000
// CHECK-NEXT: )
// CHECK-NEXT: }
// CHECK-NEXT: ]
// CHECK: UnwindInformation [
// CHECK-NEXT: RuntimeFunction {
// CHECK-NEXT: StartAddress: func {{(\+0x[A-F0-9]+ )?}}([[BeginDisp]])
// CHECK-NEXT: EndAddress: func {{(\+0x[A-F0-9]+ )?}}([[EndDisp]])
// CHECK-NEXT: UnwindInfoAddress: .xdata {{(\+0x[A-F0-9]+ )?}}([[UnwindDisp]])
// CHECK-NEXT: UnwindInfo {
// CHECK-NEXT: Version: 1
// CHECK-NEXT: Flags [
// CHECK-NEXT: ExceptionHandler
// CHECK-NEXT: ]
// CHECK-NEXT: PrologSize: 0
// CHECK-NEXT: FrameRegister: -
// CHECK-NEXT: FrameOffset: -
// CHECK-NEXT: UnwindCodeCount: 1
// CHECK-NEXT: UnwindCodes [
// CHECK-NEXT: 0x04: ALLOC_SMALL size=24
// CHECK-NEXT: ]
// CHECK-NEXT: Handler: __C_specific_handler ([[HandlerDisp]])
// CHECK-NEXT: }
// CHECK-NEXT: }
// CHECK-NEXT: ]

// Generates only one unwind code.
// Requires padding of the unwind code array.
.globl func
.def func; .scl 2; .type 32; .endef
.seh_proc func
subq $24, %rsp
.seh_stackalloc 24
.seh_handler __C_specific_handler, @except
.seh_handlerdata
.long 0xcafebabe
.text
.seh_endprologue
func:
addq $24, %rsp
ret
.seh_endproc
83 changes: 83 additions & 0 deletions test/MC/COFF/seh-align3.s
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Original file line number Diff line number Diff line change
@@ -0,0 +1,83 @@
// This test checks the alignment and padding of the unwind info.

// RUN: llvm-mc -triple x86_64-pc-win32 -filetype=obj %s | llvm-readobj -s -sd -sr -u | FileCheck %s

// CHECK: Sections [
// CHECK: Section {
// CHECK: Name: .xdata
// CHECK: RawDataSize: 16
// CHECK: RelocationCount: 1
// CHECK: Characteristics [
// CHECK-NEXT: ALIGN_4BYTES
// CHECK-NEXT: CNT_INITIALIZED_DATA
// CHECK-NEXT: MEM_READ
// CHECK-NEXT: ]
// CHECK: Relocations [
// CHECK-NEXT: [[HandlerDisp:0x[A-F0-9]+]] IMAGE_REL_AMD64_ADDR32NB __C_specific_handler
// CHECK-NEXT: ]
// CHECK: SectionData (
// CHECK-NEXT: 0000: 19000200 04D002C0 00000000 BEBAFECA
// CHECK-NEXT: )
// CHECK-NEXT: }
// CHECK-NEXT: Section {
// CHECK: Name: .pdata
// CHECK: RawDataSize: 12
// CHECK: RelocationCount: 3
// CHECK: Characteristics [
// CHECK-NEXT: IMAGE_SCN_ALIGN_4BYTES
// CHECK-NEXT: IMAGE_SCN_CNT_INITIALIZED_DATA
// CHECK-NEXT: IMAGE_SCN_MEM_READ
// CHECK-NEXT: ]
// CHECK: Relocations [
// CHECK-NEXT: [[BeginDisp:0x[A-F0-9]+]] IMAGE_REL_AMD64_ADDR32NB func
// CHECK-NEXT: [[EndDisp:0x[A-F0-9]+]] IMAGE_REL_AMD64_ADDR32NB func
// CHECK-NEXT: [[UnwindDisp:0x[A-F0-9]+]] IMAGE_REL_AMD64_ADDR32NB .xdata
// CHECK-NEXT: ]
// CHECK: SectionData (
// CHECK-NEXT: 0000: FCFFFFFF 05000000 00000000
// CHECK-NEXT: )
// CHECK-NEXT: }
// CHECK-NEXT: ]
// CHECK: UnwindInformation [
// CHECK-NEXT: RuntimeFunction {
// CHECK-NEXT: StartAddress: func {{(\+0x[A-F0-9]+ )?}}([[BeginDisp]])
// CHECK-NEXT: EndAddress: func {{(\+0x[A-F0-9]+ )?}}([[EndDisp]])
// CHECK-NEXT: UnwindInfoAddress: .xdata {{(\+0x[A-F0-9]+ )?}}([[UnwindDisp]])
// CHECK-NEXT: UnwindInfo {
// CHECK-NEXT: Version: 1
// CHECK-NEXT: Flags [
// CHECK-NEXT: ExceptionHandler
// CHECK-NEXT: TerminateHandler
// CHECK-NEXT: ]
// CHECK-NEXT: PrologSize: 0
// CHECK-NEXT: FrameRegister: -
// CHECK-NEXT: FrameOffset: -
// CHECK-NEXT: UnwindCodeCount: 2
// CHECK-NEXT: UnwindCodes [
// CHECK-NEXT: 0x04: PUSH_NONVOL reg=R13
// CHECK-NEXT: 0x02: PUSH_NONVOL reg=R12
// CHECK-NEXT: ]
// CHECK-NEXT: Handler: __C_specific_handler ([[HandlerDisp]])
// CHECK-NEXT: }
// CHECK-NEXT: }
// CHECK-NEXT: ]

// Generates two unwind codes.
// Requires no padding of the unwind code array.
.globl func
.def func; .scl 2; .type 32; .endef
.seh_proc func
push %r12
.seh_pushreg 12
push %r13
.seh_pushreg 13
.seh_handler __C_specific_handler, @except, @unwind
.seh_handlerdata
.long 0xcafebabe
.text
.seh_endprologue
func:
pop %r13
pop %r12
ret
.seh_endproc

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