[MC] Support .cfi_label #97922
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[MC] Support .cfi_label #97922
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@llvm/pr-subscribers-bolt @llvm/pr-subscribers-mc Author: Fangrui Song (MaskRay) ChangesGNU assembler 2.26 introduced the .cfi_label directive. It does not In glibc since 2018, sysdeps/riscv/start.S utilizes .cfi_label to force Full diff: https://github.com/llvm/llvm-project/pull/97922.diff 8 Files Affected:
diff --git a/llvm/include/llvm/MC/MCDwarf.h b/llvm/include/llvm/MC/MCDwarf.h
index 5052c6756c32b..d0e45ab59a92e 100644
--- a/llvm/include/llvm/MC/MCDwarf.h
+++ b/llvm/include/llvm/MC/MCDwarf.h
@@ -500,7 +500,8 @@ class MCCFIInstruction {
OpRegister,
OpWindowSave,
OpNegateRAState,
- OpGnuArgsSize
+ OpGnuArgsSize,
+ OpLabel,
};
private:
@@ -519,6 +520,7 @@ class MCCFIInstruction {
unsigned Register;
unsigned Register2;
} RR;
+ MCSymbol *CfiLabel;
} U;
OpType Operation;
SMLoc Loc;
@@ -544,6 +546,12 @@ class MCCFIInstruction {
U.RIA = {R, O, AS};
}
+ MCCFIInstruction(OpType Op, MCSymbol *L, MCSymbol *CfiLabel, SMLoc Loc)
+ : Label(L), Operation(Op), Loc(Loc) {
+ assert(Op == OpLabel);
+ U.CfiLabel = CfiLabel;
+ }
+
public:
/// .cfi_def_cfa defines a rule for computing CFA as: take address from
/// Register and add Offset to it.
@@ -664,6 +672,11 @@ class MCCFIInstruction {
return MCCFIInstruction(OpGnuArgsSize, L, 0, Size, Loc);
}
+ static MCCFIInstruction createLabel(MCSymbol *L, MCSymbol *CfiLabel,
+ SMLoc Loc) {
+ return MCCFIInstruction(OpLabel, L, CfiLabel, Loc);
+ }
+
OpType getOperation() const { return Operation; }
MCSymbol *getLabel() const { return Label; }
@@ -698,6 +711,11 @@ class MCCFIInstruction {
return U.RI.Offset;
}
+ MCSymbol *getCfiLabel() const {
+ assert(Operation == OpLabel);
+ return U.CfiLabel;
+ }
+
StringRef getValues() const {
assert(Operation == OpEscape);
return StringRef(&Values[0], Values.size());
diff --git a/llvm/include/llvm/MC/MCStreamer.h b/llvm/include/llvm/MC/MCStreamer.h
index 1d3057a140d8a..78aa12062102c 100644
--- a/llvm/include/llvm/MC/MCStreamer.h
+++ b/llvm/include/llvm/MC/MCStreamer.h
@@ -1019,6 +1019,7 @@ class MCStreamer {
SMLoc Loc = {});
virtual void emitCFIWindowSave(SMLoc Loc = {});
virtual void emitCFINegateRAState(SMLoc Loc = {});
+ virtual void emitCFILabelDirective(SMLoc Loc, StringRef Name);
virtual void emitWinCFIStartProc(const MCSymbol *Symbol, SMLoc Loc = SMLoc());
virtual void emitWinCFIEndProc(SMLoc Loc = SMLoc());
diff --git a/llvm/lib/CodeGen/CFIInstrInserter.cpp b/llvm/lib/CodeGen/CFIInstrInserter.cpp
index 87b062a16df1d..1ff01ad34b30e 100644
--- a/llvm/lib/CodeGen/CFIInstrInserter.cpp
+++ b/llvm/lib/CodeGen/CFIInstrInserter.cpp
@@ -248,6 +248,7 @@ void CFIInstrInserter::calculateOutgoingCFAInfo(MBBCFAInfo &MBBInfo) {
case MCCFIInstruction::OpWindowSave:
case MCCFIInstruction::OpNegateRAState:
case MCCFIInstruction::OpGnuArgsSize:
+ case MCCFIInstruction::OpLabel:
break;
}
if (CSRReg || CSROffset) {
diff --git a/llvm/lib/MC/MCAsmStreamer.cpp b/llvm/lib/MC/MCAsmStreamer.cpp
index 0050923f3cd9d..45c32f13e759b 100644
--- a/llvm/lib/MC/MCAsmStreamer.cpp
+++ b/llvm/lib/MC/MCAsmStreamer.cpp
@@ -356,6 +356,7 @@ class MCAsmStreamer final : public MCStreamer {
void emitCFIWindowSave(SMLoc Loc) override;
void emitCFINegateRAState(SMLoc Loc) override;
void emitCFIReturnColumn(int64_t Register) override;
+ void emitCFILabelDirective(SMLoc Loc, StringRef Name) override;
void emitWinCFIStartProc(const MCSymbol *Symbol, SMLoc Loc) override;
void emitWinCFIEndProc(SMLoc Loc) override;
@@ -2126,6 +2127,12 @@ void MCAsmStreamer::emitCFIReturnColumn(int64_t Register) {
EmitEOL();
}
+void MCAsmStreamer::emitCFILabelDirective(SMLoc Loc, StringRef Name) {
+ MCStreamer::emitCFILabelDirective(Loc, Name);
+ OS << "\t.cfi_label " << Name;
+ EmitEOL();
+}
+
void MCAsmStreamer::emitCFIBKeyFrame() {
MCStreamer::emitCFIBKeyFrame();
OS << "\t.cfi_b_key_frame";
diff --git a/llvm/lib/MC/MCDwarf.cpp b/llvm/lib/MC/MCDwarf.cpp
index 321a66ee5abc4..efafd555c5c5c 100644
--- a/llvm/lib/MC/MCDwarf.cpp
+++ b/llvm/lib/MC/MCDwarf.cpp
@@ -1465,6 +1465,9 @@ void FrameEmitterImpl::emitCFIInstruction(const MCCFIInstruction &Instr) {
case MCCFIInstruction::OpEscape:
Streamer.emitBytes(Instr.getValues());
return;
+ case MCCFIInstruction::OpLabel:
+ Streamer.emitLabel(Instr.getCfiLabel(), Instr.getLoc());
+ return;
}
llvm_unreachable("Unhandled case in switch");
}
diff --git a/llvm/lib/MC/MCParser/AsmParser.cpp b/llvm/lib/MC/MCParser/AsmParser.cpp
index 707edb0481a61..f3caa90eedfb1 100644
--- a/llvm/lib/MC/MCParser/AsmParser.cpp
+++ b/llvm/lib/MC/MCParser/AsmParser.cpp
@@ -520,6 +520,7 @@ class AsmParser : public MCAsmParser {
DK_CFI_UNDEFINED,
DK_CFI_REGISTER,
DK_CFI_WINDOW_SAVE,
+ DK_CFI_LABEL,
DK_CFI_B_KEY_FRAME,
DK_MACROS_ON,
DK_MACROS_OFF,
@@ -622,6 +623,7 @@ class AsmParser : public MCAsmParser {
bool parseDirectiveCFIReturnColumn(SMLoc DirectiveLoc);
bool parseDirectiveCFISignalFrame(SMLoc DirectiveLoc);
bool parseDirectiveCFIUndefined(SMLoc DirectiveLoc);
+ bool parseDirectiveCFILabel(SMLoc DirectiveLoc);
// macro directives
bool parseDirectivePurgeMacro(SMLoc DirectiveLoc);
@@ -2224,6 +2226,8 @@ bool AsmParser::parseStatement(ParseStatementInfo &Info,
return parseDirectiveCFIRegister(IDLoc);
case DK_CFI_WINDOW_SAVE:
return parseDirectiveCFIWindowSave(IDLoc);
+ case DK_CFI_LABEL:
+ return parseDirectiveCFILabel(IDLoc);
case DK_MACROS_ON:
case DK_MACROS_OFF:
return parseDirectiveMacrosOnOff(IDVal);
@@ -4488,6 +4492,19 @@ bool AsmParser::parseDirectiveCFIUndefined(SMLoc DirectiveLoc) {
return false;
}
+/// parseDirectiveCFILabel
+/// ::= .cfi_label label
+bool AsmParser::parseDirectiveCFILabel(SMLoc Loc) {
+ StringRef Name;
+ Loc = Lexer.getLoc();
+ if (parseIdentifier(Name))
+ return TokError("expected identifier");
+ if (parseEOL())
+ return true;
+ getStreamer().emitCFILabelDirective(Loc, Name);
+ return false;
+}
+
/// parseDirectiveAltmacro
/// ::= .altmacro
/// ::= .noaltmacro
@@ -5560,6 +5577,7 @@ void AsmParser::initializeDirectiveKindMap() {
DirectiveKindMap[".cfi_undefined"] = DK_CFI_UNDEFINED;
DirectiveKindMap[".cfi_register"] = DK_CFI_REGISTER;
DirectiveKindMap[".cfi_window_save"] = DK_CFI_WINDOW_SAVE;
+ DirectiveKindMap[".cfi_label"] = DK_CFI_LABEL;
DirectiveKindMap[".cfi_b_key_frame"] = DK_CFI_B_KEY_FRAME;
DirectiveKindMap[".cfi_mte_tagged_frame"] = DK_CFI_MTE_TAGGED_FRAME;
DirectiveKindMap[".macros_on"] = DK_MACROS_ON;
diff --git a/llvm/lib/MC/MCStreamer.cpp b/llvm/lib/MC/MCStreamer.cpp
index a3f67941c1015..1594bd3231abe 100644
--- a/llvm/lib/MC/MCStreamer.cpp
+++ b/llvm/lib/MC/MCStreamer.cpp
@@ -689,6 +689,13 @@ void MCStreamer::emitCFIReturnColumn(int64_t Register) {
CurFrame->RAReg = Register;
}
+void MCStreamer::emitCFILabelDirective(SMLoc Loc, StringRef Name) {
+ MCSymbol *Label = emitCFILabel();
+ MCSymbol *Sym = getContext().getOrCreateSymbol(Name);
+ if (MCDwarfFrameInfo *F = getCurrentDwarfFrameInfo())
+ F->Instructions.push_back(MCCFIInstruction::createLabel(Label, Sym, Loc));
+}
+
WinEH::FrameInfo *MCStreamer::EnsureValidWinFrameInfo(SMLoc Loc) {
const MCAsmInfo *MAI = Context.getAsmInfo();
if (!MAI->usesWindowsCFI()) {
diff --git a/llvm/test/MC/ELF/cfi-label.s b/llvm/test/MC/ELF/cfi-label.s
new file mode 100644
index 0000000000000..e0df9b8a1b253
--- /dev/null
+++ b/llvm/test/MC/ELF/cfi-label.s
@@ -0,0 +1,61 @@
+# RUN: llvm-mc -triple x86_64 %s | FileCheck %s --check-prefix=ASM
+# RUN: llvm-mc -filetype=obj -triple=x86_64 %s -o %t
+# RUN: llvm-readelf -sX %t | FileCheck %s --check-prefix=SYMTAB
+# RUN: llvm-dwarfdump --eh-frame %t | FileCheck %s
+
+# RUN: not llvm-mc -filetype=obj -triple=x86_64 --defsym ERR=1 %s -o /dev/null 2>&1 | \
+# RUN: FileCheck %s --check-prefix=ERR --implicit-check-not=error:
+
+# ASM: nop
+# ASM-NEXT: .cfi_label cfi1
+# ASM-NEXT: .cfi_escape 0x00
+# ASM: .globl cfi2
+# ASM-NEXT: .cfi_label cfi2
+# ASM: nop
+# ASM-NEXT: .cfi_label .Lcfi3
+
+# SYMTAB: 000000000000002b 0 NOTYPE LOCAL DEFAULT 3 (.eh_frame) cfi1
+# SYMTAB: 000000000000002d 0 NOTYPE GLOBAL DEFAULT 3 (.eh_frame) cfi2
+# SYMTAB-NOT: {{.}}
+
+# CHECK: DW_CFA_remember_state:
+# CHECK-NEXT: DW_CFA_advance_loc: 1 to 0x1
+# CHECK-NEXT: DW_CFA_nop:
+# CHECK-NEXT: DW_CFA_advance_loc: 1 to 0x2
+# CHECK-NEXT: DW_CFA_nop:
+# CHECK-NEXT: DW_CFA_nop:
+# CHECK-NEXT: DW_CFA_advance_loc: 1 to 0x3
+# CHECK-NEXT: DW_CFA_nop:
+# CHECK-NEXT: DW_CFA_nop:
+# CHECK-NEXT: DW_CFA_nop:
+# CHECK-NEXT: DW_CFA_restore_state:
+
+.globl foo
+foo:
+.cfi_startproc
+.cfi_remember_state
+nop
+.cfi_label cfi1
+.cfi_escape 0
+nop
+.globl cfi2
+.cfi_label cfi2
+.cfi_escape 0, 0
+nop
+.cfi_label .Lcfi3
+.cfi_escape 0, 0, 0
+.cfi_restore_state
+ret
+
+# ERR: [[#@LINE+10]]:1: error: this directive must appear between .cfi_startproc and .cfi_endproc directives
+.ifdef ERR
+# ERR: [[#@LINE+1]]:12: error: symbol 'foo' is already defined
+.cfi_label foo
+# ERR: [[#@LINE+1]]:12: error: symbol '.Lcfi3' is already defined
+.cfi_label .Lcfi3
+.endif
+.cfi_endproc
+
+.ifdef ERR
+.cfi_label after_endproc
+.endif
|
Created using spr 1.3.5-bogner
MaskRay
requested review from
aaupov,
maksfb,
rafaelauler,
ayermolo and
dcci
as code owners
searlmc1
pushed a commit
to ROCm/llvm-project
that referenced
this pull request
Jul 9, 2024
GNU assembler 2.26 introduced the .cfi_label directive. It does not expand to any CFI instructions, but defines a label in .eh_frame/.debug_frame, which can be used by runtime patching code to locate the FDE. .cfi_label is not allowed for CIE's initial instructions, and can therefore be used to force the next instruction to be placed in a FDE instead of a CIE. In glibc since 2018, sysdeps/riscv/start.S utilizes .cfi_label to force DW_CFA_undefined to be placed in a FDE. arc/csky/loongarch ports have copied this use. ``` .cfi_startproc // DW_CFA_undefined is allowed for CIE's initial instructions. // Without .cfi_label, gas would place DW_CFA_undefined in a CIE. .cfi_label .Ldummy .cfi_undefined ra .cfi_endproc ``` No CFI instruction is associated with .cfi_label, so the `case MCCFIInstruction::OpLabel:` code in BOLT is unreachable and onlt to make -Wswitch happy. Close llvm#97222 Pull Request: llvm#97922 Change-Id: Ic236d33bf52ac5631bd202c2896d23463c8e099b
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GNU assembler 2.26 introduced the .cfi_label directive. It does not
expand to any CFI instructions, but defines a label in
.eh_frame/.debug_frame, which can be used by runtime patching code to
locate the FDE. .cfi_label is not allowed for CIE's initial
instructions, and can therefore be used to force the next instruction to
be placed in a FDE instead of a CIE.
In glibc since 2018, sysdeps/riscv/start.S utilizes .cfi_label to force
DW_CFA_undefined to be placed in a FDE. arc/csky/loongarch ports have
copied this use.
No CFI instruction is associated with .cfi_label, so the
case MCCFIInstruction::OpLabel:code in BOLT is unreachable and onlt to make-Wswitch happy.
Close #97222