forked from OSchip/llvm-project
[patch] Adjust behavior of FDE cross-section relocs for targets that don't support abs-differences.
Modern versions of OSX/Darwin's ld (ld64 > 97.17) have an optimisation present that allows the back end to omit relocations (and replace them with an absolute difference) for FDE some text section refs. This patch allows a backend to opt-in to this behaviour by setting "DwarfFDESymbolsUseAbsDiff". At present, this is only enabled for modern x86 OSX ports. test changes by David Fang. llvm-svn: 198744
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@ -292,6 +292,10 @@ namespace llvm {
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/// uses relocations for references to other .debug_* sections.
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bool DwarfUsesRelocationsAcrossSections;
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/// DwarfFDESymbolsUseAbsDiff - true if DWARF FDE symbol reference
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/// relocations should be replaced by an absolute difference.
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bool DwarfFDESymbolsUseAbsDiff;
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/// DwarfRegNumForCFI - True if dwarf register numbers are printed
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/// instead of symbolic register names in .cfi_* directives.
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bool DwarfRegNumForCFI; // Defaults to false;
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@ -513,6 +517,9 @@ namespace llvm {
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bool doesDwarfUseRelocationsAcrossSections() const {
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return DwarfUsesRelocationsAcrossSections;
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}
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bool doDwarfFDESymbolsUseAbsDiff() const {
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return DwarfFDESymbolsUseAbsDiff;
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}
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bool useDwarfRegNumForCFI() const {
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return DwarfRegNumForCFI;
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}
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@ -84,6 +84,7 @@ MCAsmInfo::MCAsmInfo() {
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SupportsDebugInformation = false;
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ExceptionsType = ExceptionHandling::None;
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DwarfUsesRelocationsAcrossSections = true;
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DwarfFDESymbolsUseAbsDiff = false;
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DwarfRegNumForCFI = false;
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NeedsDwarfSectionOffsetDirective = false;
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UseParensForSymbolVariant = false;
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@ -839,8 +839,9 @@ static unsigned getSizeForEncoding(MCStreamer &streamer,
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}
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}
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static void EmitSymbol(MCStreamer &streamer, const MCSymbol &symbol,
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unsigned symbolEncoding, const char *comment = 0) {
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static void EmitFDESymbol(MCStreamer &streamer, const MCSymbol &symbol,
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unsigned symbolEncoding, bool isEH,
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const char *comment = 0) {
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MCContext &context = streamer.getContext();
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const MCAsmInfo *asmInfo = context.getAsmInfo();
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const MCExpr *v = asmInfo->getExprForFDESymbol(&symbol,
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@ -848,7 +849,10 @@ static void EmitSymbol(MCStreamer &streamer, const MCSymbol &symbol,
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streamer);
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unsigned size = getSizeForEncoding(streamer, symbolEncoding);
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if (streamer.isVerboseAsm() && comment) streamer.AddComment(comment);
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streamer.EmitAbsValue(v, size);
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if (asmInfo->doDwarfFDESymbolsUseAbsDiff() && isEH)
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streamer.EmitAbsValue(v, size);
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else
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streamer.EmitValue(v, size);
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}
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static void EmitPersonality(MCStreamer &streamer, const MCSymbol &symbol,
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@ -1347,7 +1351,7 @@ MCSymbol *FrameEmitterImpl::EmitFDE(MCStreamer &streamer,
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unsigned PCEncoding = IsEH ? MOFI->getFDEEncoding(UsingCFI)
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: (unsigned)dwarf::DW_EH_PE_absptr;
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unsigned PCSize = getSizeForEncoding(streamer, PCEncoding);
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EmitSymbol(streamer, *frame.Begin, PCEncoding, "FDE initial location");
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EmitFDESymbol(streamer, *frame.Begin, PCEncoding, IsEH, "FDE initial location");
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// PC Range
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const MCExpr *Range = MakeStartMinusEndExpr(streamer, *frame.Begin,
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@ -1367,8 +1371,8 @@ MCSymbol *FrameEmitterImpl::EmitFDE(MCStreamer &streamer,
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// Augmentation Data
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if (frame.Lsda)
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EmitSymbol(streamer, *frame.Lsda, frame.LsdaEncoding,
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"Language Specific Data Area");
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EmitFDESymbol(streamer, *frame.Lsda, frame.LsdaEncoding, true,
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"Language Specific Data Area");
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}
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// Call Frame Instructions
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@ -71,6 +71,11 @@ X86MCAsmInfoDarwin::X86MCAsmInfoDarwin(const Triple &T) {
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// rather than OS version
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if (T.isMacOSX() && T.isMacOSXVersionLT(10, 6))
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HasWeakDefCanBeHiddenDirective = false;
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// FIXME: this should not depend on the target OS version, but on the ld64
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// version in use. From at least >= ld64-97.17 (Xcode 3.2.6) the abs-ified
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// FDE relocs may be used.
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DwarfFDESymbolsUseAbsDiff = T.isMacOSX() && !T.isMacOSXVersionLT(10, 6);
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}
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X86_64MCAsmInfoDarwin::X86_64MCAsmInfoDarwin(const Triple &Triple)
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@ -1,4 +1,9 @@
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; RUN: llc < %s -mtriple=x86_64-apple-macosx -disable-cfi | FileCheck %s
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; RUN: llc < %s -mtriple=x86_64-apple-macosx10.7 -disable-cfi | FileCheck --check-prefix=CHECK-64-D11 %s
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; RUN: llc < %s -mtriple=x86_64-apple-macosx10.6 -disable-cfi | FileCheck %s
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; RUN: llc < %s -mtriple=x86_64-apple-macosx10.5 -disable-cfi | FileCheck --check-prefix=CHECK-64-D89 %s
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; RUN: llc < %s -mtriple=i686-apple-macosx10.6 -disable-cfi | FileCheck --check-prefix=CHECK-I686-D10 %s
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; RUN: llc < %s -mtriple=i686-apple-macosx10.5 -disable-cfi | FileCheck --check-prefix=CHECK-I686-D89 %s
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; RUN: llc < %s -mtriple=i686-apple-macosx10.4 -disable-cfi | FileCheck --check-prefix=CHECK-I686-D89 %s
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define private void @foo() {
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ret void
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@ -19,3 +24,44 @@ define void @bar() {
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; CHECK: Ltmp19:
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; CHECK-NEXT: Ltmp20 = Ltmp2-Ltmp19 ## FDE initial location
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; CHECK-NEXT: .quad Ltmp20
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; CHECK-64-D11: Ltmp13:
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; CHECK-64-D11-NEXT: Ltmp14 = L_foo-Ltmp13 ## FDE initial location
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; CHECK-64-D11-NEXT: .quad Ltmp14
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; CHECK-64-D11: Ltmp20:
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; CHECK-64-D11-NEXT: Ltmp21 = Ltmp2-Ltmp20 ## FDE initial location
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; CHECK-64-D11-NEXT: .quad Ltmp21
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; CHECK-64-D89: Ltmp12:
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; CHECK-64-D89-NEXT: .quad L_foo-Ltmp12 ## FDE initial location
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; CHECK-64-D89-NEXT: Ltmp13 = (Ltmp0-L_foo)-0 ## FDE address range
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; CHECK-64-D89-NEXT: .quad Ltmp13
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; CHECK-64-D89: Ltmp18:
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; CHECK-64-D89-NEXT: .quad Ltmp2-Ltmp18 ## FDE initial location
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; CHECK-64-D89-NEXT: Ltmp19 = (Ltmp4-Ltmp2)-0 ## FDE address range
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; CHECK-64-D89-NEXT: .quad Ltmp19
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; CHECK-I686-D10: Ltmp12:
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; CHECK-I686-D10-NEXT: Ltmp13 = L_foo-Ltmp12 ## FDE initial location
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; CHECK-I686-D10-NEXT: .long Ltmp13
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; CHECK-I686-D10: Ltmp19:
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; CHECK-I686-D10-NEXT: Ltmp20 = Ltmp2-Ltmp19 ## FDE initial location
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; CHECK-I686-D10-NEXT: .long Ltmp20
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; CHECK-I686-D89: Ltmp12:
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; CHECK-I686-D89-NEXT: .long L_foo-Ltmp12 ## FDE initial location
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; CHECK-I686-D89-NEXT: Ltmp13 = (Ltmp0-L_foo)-0 ## FDE address range
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; CHECK-I686-D89-NEXT: .long Ltmp13
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; CHECK-I686-D89: Ltmp18:
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; CHECK-I686-D89-NEXT: .long Ltmp2-Ltmp18 ## FDE initial location
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; CHECK-I686-D89-NEXT: Ltmp19 = (Ltmp4-Ltmp2)-0 ## FDE address range
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; CHECK-I686-D89-NEXT: .long Ltmp19
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