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CodeGen: avoid emitting unnecessary CFI

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Remove unnecessary clutter in assembly output.  When using SjLj EH, the CFI is
not actually used for anything.  Do not emit the CFI needlessly.  The minor test
adjustments are interesting.  The prologue test was just overzealous matcching.
The interesting case is the LSDA change.  It was originally added to ensure that
various compilations did not mangle the name (it explicitly checked the name!).
However, subsequent cleanups made it more reliant on the CFI to find the name.
Parse the generated code flow to generically find the label still.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@275614 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Saleem Abdulrasool 2016-07-15 21:10:29 +00:00
parent bf4114e90b
commit 1083a5297a
3 changed files with 10 additions and 8 deletions
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9
lib/CodeGen/AsmPrinter/DwarfCFIException.cpp
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@ -66,13 +66,13 @@ DwarfCFIException::~DwarfCFIException() {}
/// endModule - Emit all exception information that should come after the
/// content.
void DwarfCFIException::endModule() {
if (moveTypeModule == AsmPrinter::CFI_M_Debug)
Asm->OutStreamer->EmitCFISections(false, true);
// SjLj uses this pass and it doesn't need this info.
if (!Asm->MAI->usesCFIForEH())
return;
if (moveTypeModule == AsmPrinter::CFI_M_Debug)
Asm->OutStreamer->EmitCFISections(false, true);
const TargetLoweringObjectFile &TLOF = Asm->getObjFileLowering();
unsigned PerEncoding = TLOF.getPersonalityEncoding();
@ -133,7 +133,8 @@ void DwarfCFIException::beginFunction(const MachineFunction *MF) {
shouldEmitLSDA = shouldEmitPersonality &&
LSDAEncoding != dwarf::DW_EH_PE_omit;
shouldEmitCFI = shouldEmitPersonality || shouldEmitMoves;
shouldEmitCFI = MF->getMMI().getContext().getAsmInfo()->usesCFIForEH() &&
(shouldEmitPersonality || shouldEmitMoves);
beginFragment(&*MF->begin(), getExceptionSym);
}

8
test/CodeGen/ARM/2009-08-31-LSDA-Name.ll
View File

@ -1,8 +1,10 @@
; RUN: llc < %s -mtriple=arm-apple-darwin9 -march=arm | FileCheck %s
; CHECK: .cfi_lsda 16, [[LABEL:.*]]
; CHECK: .long [[LABEL]]-
; CHECK: [[LABEL]]:
; CHECK: ldr r0, [[CPI_PERSONALITY:[A-Za-z0-9_]+]]
; CHECK: ldr r0, [[CPI_LSDA:[A-Za-z0-9_]+]]
; CHECK: [[CPI_LSDA]]:
; CHECK: .long [[LSDA_LABEL:[A-Za-z0-9_]+]]-
; CHECK: [[LSDA_LABEL]]:
; CHECK: .byte 255 @ @LPStart Encoding = omit
%struct.A = type { i32* }

1
test/DebugInfo/ARM/prologue_end.ll
View File

@ -9,7 +9,6 @@
define void @prologue_end_test() nounwind uwtable !dbg !4 {
; CHECK: prologue_end_test:
; CHECK: .cfi_startproc
; CHECK: push {r7, lr}
; CHECK: {{mov r7, sp|add r7, sp}}
; CHECK: sub sp