Support SFrame command-line and .cfi_section syntax #149935
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This PR adds support for the llvm-mc command-line flag "--gsframe" and adds ".sframe" to the legal values passed ".cfi_section". It plumbs the option through the cfi handling code a fair amount. Code to support actual section generation follows in a future PR. These options match the gnu-assembler's support syntax for sframes, on both the command line and in assembly files. First in a series of changes that will allow llvm-mc to produce sframe .cfi sections. For more information about sframes, see https://sourceware.org/binutils/docs-2.44/sframe-spec.html and the llvm-RFC here: https://discourse.llvm.org/t/rfc-adding-sframe-support-to-llvm/86900
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@llvm/pr-subscribers-mc @llvm/pr-subscribers-debuginfo Author: None (Sterling-Augustine) ChangesThis PR adds support for the llvm-mc command-line flag "--gsframe" and adds ".sframe" to the legal values passed ".cfi_section". It plumbs the option through the cfi handling code a fair amount. Code to support actual section generation follows in a future PR. These options match the gnu-assembler's support syntax for sframes, on both the command line and in assembly files. First in a series of changes that will allow llvm-mc to produce sframe .cfi sections. For more information about sframes, see https://sourceware.org/binutils/docs-2.44/sframe-spec.html and the llvm-RFC here: Full diff: https://github.com/llvm/llvm-project/pull/149935.diff 13 Files Affected:
diff --git a/llvm/include/llvm/MC/MCObjectStreamer.h b/llvm/include/llvm/MC/MCObjectStreamer.h
index 2ceeba22abccd..aea93e9dc7e4f 100644
--- a/llvm/include/llvm/MC/MCObjectStreamer.h
+++ b/llvm/include/llvm/MC/MCObjectStreamer.h
@@ -40,6 +40,7 @@ class MCObjectStreamer : public MCStreamer {
std::unique_ptr<MCAssembler> Assembler;
bool EmitEHFrame;
bool EmitDebugFrame;
+ bool EmitSFrame;
struct PendingAssignment {
MCSymbol *Symbol;
@@ -70,7 +71,7 @@ class MCObjectStreamer : public MCStreamer {
void emitFrames(MCAsmBackend *MAB);
MCSymbol *emitCFILabel() override;
- void emitCFISections(bool EH, bool Debug) override;
+ void emitCFISections(bool EH, bool Debug, bool SFrame) override;
public:
void visitUsedSymbol(const MCSymbol &Sym) override;
diff --git a/llvm/include/llvm/MC/MCStreamer.h b/llvm/include/llvm/MC/MCStreamer.h
index 4bfc8f921ef11..dfaf3487e11a7 100644
--- a/llvm/include/llvm/MC/MCStreamer.h
+++ b/llvm/include/llvm/MC/MCStreamer.h
@@ -986,7 +986,7 @@ class LLVM_ABI MCStreamer {
const MCSymbol *Lo);
virtual MCSymbol *getDwarfLineTableSymbol(unsigned CUID);
- virtual void emitCFISections(bool EH, bool Debug);
+ virtual void emitCFISections(bool EH, bool Debug, bool SFrame);
void emitCFIStartProc(bool IsSimple, SMLoc Loc = SMLoc());
void emitCFIEndProc();
virtual void emitCFIDefCfa(int64_t Register, int64_t Offset, SMLoc Loc = {});
diff --git a/llvm/include/llvm/MC/MCTargetOptions.h b/llvm/include/llvm/MC/MCTargetOptions.h
index d95adf92b9a83..235d58d585b40 100644
--- a/llvm/include/llvm/MC/MCTargetOptions.h
+++ b/llvm/include/llvm/MC/MCTargetOptions.h
@@ -102,6 +102,9 @@ class MCTargetOptions {
// functions on Darwins.
bool EmitCompactUnwindNonCanonical : 1;
+ // Whether to emit SFrame unwind sections.
+ bool EmitSFrameUnwind : 1;
+
// Whether or not to use full register names on PowerPC.
bool PPCUseFullRegisterNames : 1;
diff --git a/llvm/include/llvm/MC/MCTargetOptionsCommandFlags.h b/llvm/include/llvm/MC/MCTargetOptionsCommandFlags.h
index b057effd88128..adfdccdb5ab77 100644
--- a/llvm/include/llvm/MC/MCTargetOptionsCommandFlags.h
+++ b/llvm/include/llvm/MC/MCTargetOptionsCommandFlags.h
@@ -40,6 +40,8 @@ LLVM_ABI EmitDwarfUnwindType getEmitDwarfUnwind();
LLVM_ABI bool getEmitCompactUnwindNonCanonical();
+LLVM_ABI bool getEmitSFrameUnwind();
+
LLVM_ABI bool getShowMCInst();
LLVM_ABI bool getFatalWarnings();
diff --git a/llvm/lib/CodeGen/AsmPrinter/ARMException.cpp b/llvm/lib/CodeGen/AsmPrinter/ARMException.cpp
index de6ebcf0c3419..51342c6b91345 100644
--- a/llvm/lib/CodeGen/AsmPrinter/ARMException.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/ARMException.cpp
@@ -39,7 +39,7 @@ void ARMException::beginFunction(const MachineFunction *MF) {
if (CFISecType == AsmPrinter::CFISection::Debug) {
if (!hasEmittedCFISections) {
if (Asm->getModuleCFISectionType() == AsmPrinter::CFISection::Debug)
- Asm->OutStreamer->emitCFISections(false, true);
+ Asm->OutStreamer->emitCFISections(false, true, false);
hasEmittedCFISections = true;
}
diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfCFIException.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfCFIException.cpp
index 4fac4bbc98477..6b8d08cb201d6 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfCFIException.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfCFIException.cpp
@@ -109,9 +109,11 @@ void DwarfCFIException::beginBasicBlockSection(const MachineBasicBlock &MBB) {
// chose not to be verbose in that case. And with `ForceDwarfFrameSection`,
// we should always emit .debug_frame.
if (CFISecType == AsmPrinter::CFISection::Debug ||
- Asm->TM.Options.ForceDwarfFrameSection)
+ Asm->TM.Options.ForceDwarfFrameSection ||
+ Asm->TM.Options.MCOptions.EmitSFrameUnwind)
Asm->OutStreamer->emitCFISections(
- CFISecType == AsmPrinter::CFISection::EH, true);
+ CFISecType == AsmPrinter::CFISection::EH, true,
+ Asm->TM.Options.MCOptions.EmitSFrameUnwind);
hasEmittedCFISections = true;
}
diff --git a/llvm/lib/MC/MCAsmStreamer.cpp b/llvm/lib/MC/MCAsmStreamer.cpp
index 67c53e01a6111..7119ef4a2bbcd 100644
--- a/llvm/lib/MC/MCAsmStreamer.cpp
+++ b/llvm/lib/MC/MCAsmStreamer.cpp
@@ -345,7 +345,7 @@ class MCAsmStreamer final : public MCStreamer {
void emitIdent(StringRef IdentString) override;
void emitCFIBKeyFrame() override;
void emitCFIMTETaggedFrame() override;
- void emitCFISections(bool EH, bool Debug) override;
+ void emitCFISections(bool EH, bool Debug, bool SFrame) override;
void emitCFIDefCfa(int64_t Register, int64_t Offset, SMLoc Loc) override;
void emitCFIDefCfaOffset(int64_t Offset, SMLoc Loc) override;
void emitCFIDefCfaRegister(int64_t Register, SMLoc Loc) override;
@@ -1906,15 +1906,24 @@ void MCAsmStreamer::emitIdent(StringRef IdentString) {
EmitEOL();
}
-void MCAsmStreamer::emitCFISections(bool EH, bool Debug) {
- MCStreamer::emitCFISections(EH, Debug);
+void MCAsmStreamer::emitCFISections(bool EH, bool Debug, bool SFrame) {
+ MCStreamer::emitCFISections(EH, Debug, SFrame);
OS << "\t.cfi_sections ";
+ bool C = false;
if (EH) {
OS << ".eh_frame";
- if (Debug)
- OS << ", .debug_frame";
- } else if (Debug) {
+ C = true;
+ }
+ if (Debug) {
+ if (C)
+ OS << ", ";
OS << ".debug_frame";
+ C = true;
+ }
+ if (SFrame) {
+ if (C)
+ OS << ", ";
+ OS << ".sframe";
}
EmitEOL();
diff --git a/llvm/lib/MC/MCObjectStreamer.cpp b/llvm/lib/MC/MCObjectStreamer.cpp
index 42f4cf49d7f38..d7f4be1bfb573 100644
--- a/llvm/lib/MC/MCObjectStreamer.cpp
+++ b/llvm/lib/MC/MCObjectStreamer.cpp
@@ -130,10 +130,11 @@ void MCObjectStreamer::visitUsedSymbol(const MCSymbol &Sym) {
Assembler->registerSymbol(Sym);
}
-void MCObjectStreamer::emitCFISections(bool EH, bool Debug) {
- MCStreamer::emitCFISections(EH, Debug);
+void MCObjectStreamer::emitCFISections(bool EH, bool Debug, bool SFrame) {
+ MCStreamer::emitCFISections(EH, Debug, SFrame);
EmitEHFrame = EH;
EmitDebugFrame = Debug;
+ EmitSFrame = SFrame;
}
void MCObjectStreamer::emitValueImpl(const MCExpr *Value, unsigned Size,
diff --git a/llvm/lib/MC/MCParser/AsmParser.cpp b/llvm/lib/MC/MCParser/AsmParser.cpp
index d0b6ea4cfd562..eda5e8c37f7b8 100644
--- a/llvm/lib/MC/MCParser/AsmParser.cpp
+++ b/llvm/lib/MC/MCParser/AsmParser.cpp
@@ -4093,27 +4093,30 @@ bool AsmParser::parseDirectiveCVFPOData() {
}
/// parseDirectiveCFISections
-/// ::= .cfi_sections section [, section]
+/// ::= .cfi_sections section [, section][, section]
bool AsmParser::parseDirectiveCFISections() {
StringRef Name;
bool EH = false;
bool Debug = false;
+ bool SFrame = false;
if (!parseOptionalToken(AsmToken::EndOfStatement)) {
for (;;) {
if (parseIdentifier(Name))
- return TokError("expected .eh_frame or .debug_frame");
+ return TokError("expected .eh_frame, .debug_frame, or .sframe");
if (Name == ".eh_frame")
EH = true;
else if (Name == ".debug_frame")
Debug = true;
+ else if (Name == ".sframe")
+ SFrame = true;
if (parseOptionalToken(AsmToken::EndOfStatement))
break;
if (parseComma())
return true;
}
}
- getStreamer().emitCFISections(EH, Debug);
+ getStreamer().emitCFISections(EH, Debug, SFrame);
return false;
}
diff --git a/llvm/lib/MC/MCStreamer.cpp b/llvm/lib/MC/MCStreamer.cpp
index 30198c97d8ab9..e14a32f5dc0ce 100644
--- a/llvm/lib/MC/MCStreamer.cpp
+++ b/llvm/lib/MC/MCStreamer.cpp
@@ -415,7 +415,7 @@ void MCStreamer::emitLabel(MCSymbol *Symbol, SMLoc Loc) {
void MCStreamer::emitConditionalAssignment(MCSymbol *Symbol,
const MCExpr *Value) {}
-void MCStreamer::emitCFISections(bool EH, bool Debug) {}
+void MCStreamer::emitCFISections(bool EH, bool Debug, bool SFrame) {}
void MCStreamer::emitCFIStartProc(bool IsSimple, SMLoc Loc) {
if (!FrameInfoStack.empty() &&
diff --git a/llvm/lib/MC/MCTargetOptionsCommandFlags.cpp b/llvm/lib/MC/MCTargetOptionsCommandFlags.cpp
index 2adc29172f9dd..ff95ff78fd53a 100644
--- a/llvm/lib/MC/MCTargetOptionsCommandFlags.cpp
+++ b/llvm/lib/MC/MCTargetOptionsCommandFlags.cpp
@@ -41,6 +41,7 @@ MCOPT(int, DwarfVersion)
MCOPT(bool, Dwarf64)
MCOPT(EmitDwarfUnwindType, EmitDwarfUnwind)
MCOPT(bool, EmitCompactUnwindNonCanonical)
+MCOPT(bool, EmitSFrameUnwind)
MCOPT(bool, ShowMCInst)
MCOPT(bool, FatalWarnings)
MCOPT(bool, NoWarn)
@@ -105,6 +106,11 @@ llvm::mc::RegisterMCTargetOptionsFlags::RegisterMCTargetOptionsFlags() {
false)); // By default, use DWARF for non-canonical personalities.
MCBINDOPT(EmitCompactUnwindNonCanonical);
+ static cl::opt<bool> EmitSFrameUnwind(
+ "gsframe", cl::desc("Whether to emit .sframe unwind sections."),
+ cl::init(false));
+ MCBINDOPT(EmitSFrameUnwind);
+
static cl::opt<bool> ShowMCInst(
"asm-show-inst",
cl::desc("Emit internal instruction representation to assembly file"));
@@ -188,6 +194,7 @@ MCTargetOptions llvm::mc::InitMCTargetOptionsFromFlags() {
Options.X86Sse2Avx = getX86Sse2Avx();
Options.EmitDwarfUnwind = getEmitDwarfUnwind();
Options.EmitCompactUnwindNonCanonical = getEmitCompactUnwindNonCanonical();
+ Options.EmitSFrameUnwind = getEmitSFrameUnwind();
Options.AsSecureLogFile = getAsSecureLogFile();
return Options;
diff --git a/llvm/test/MC/ELF/AArch64/cfi.s b/llvm/test/MC/ELF/AArch64/cfi.s
index 6bdf03cc7bb85..7047f92bab8fe 100644
--- a/llvm/test/MC/ELF/AArch64/cfi.s
+++ b/llvm/test/MC/ELF/AArch64/cfi.s
@@ -557,12 +557,14 @@ f37:
// CHECK-NEXT: }
.ifdef ERR
-// ERR: [[#@LINE+1]]:15: error: expected .eh_frame or .debug_frame
+// ERR: [[#@LINE+1]]:15: error: expected .eh_frame, .debug_frame, or .sframe
.cfi_sections $
// ERR: [[#@LINE+1]]:28: error: expected comma
.cfi_sections .debug_frame $
// ERR: [[#@LINE+1]]:39: error: expected comma
.cfi_sections .debug_frame, .eh_frame $
+// ERR: [[#@LINE+1]]:48: error: expected comma
+.cfi_sections .debug_frame, .eh_frame, .sframe $
// ERR: [[#@LINE+1]]:16: error: unexpected token
.cfi_startproc $
diff --git a/llvm/test/MC/ELF/cfi.s b/llvm/test/MC/ELF/cfi.s
index 3bd16aec4613e..b7f937104dbf2 100644
--- a/llvm/test/MC/ELF/cfi.s
+++ b/llvm/test/MC/ELF/cfi.s
@@ -445,12 +445,14 @@ f37:
// CHECK: }
.ifdef ERR
-// ERR: [[#@LINE+1]]:15: error: expected .eh_frame or .debug_frame
+// ERR: [[#@LINE+1]]:15: error: expected .eh_frame, .debug_frame, or .sframe
.cfi_sections $
// ERR: [[#@LINE+1]]:28: error: expected comma
.cfi_sections .debug_frame $
// ERR: [[#@LINE+1]]:39: error: expected comma
.cfi_sections .debug_frame, .eh_frame $
+// ERR: [[#@LINE+1]]:48: error: expected comma
+.cfi_sections .debug_frame, .eh_frame, .sframe $
// ERR: [[#@LINE+1]]:16: error: unexpected token
.cfi_startproc $
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lenary
approved these changes
Jul 22, 2025
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This PR adds support for the llvm-mc command-line flag "--gsframe" and adds ".sframe" to the legal values passed ".cfi_section". It plumbs the option through the cfi handling code a fair amount. Code to support actual section generation follows in a future PR.
These options match the gnu-assembler's support syntax for sframes, on both the command line and in assembly files.
First in a series of changes that will allow llvm-mc to produce sframe .cfi sections. For more information about sframes, see https://sourceware.org/binutils/docs-2.44/sframe-spec.html
and the llvm-RFC here:
https://discourse.llvm.org/t/rfc-adding-sframe-support-to-llvm/86900