[llvm] r275614 - CodeGen: avoid emitting unnecessary CFI

[Saleem Abdulrasool via llvm-commits]

Author: compnerd
Date: Fri Jul 15 16:10:29 2016
New Revision: 275614

URL: http://llvm.org/viewvc/llvm-project?rev=275614&view=rev
Log:
CodeGen: avoid emitting unnecessary CFI

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.

Modified:
    llvm/trunk/lib/CodeGen/AsmPrinter/DwarfCFIException.cpp
    llvm/trunk/test/CodeGen/ARM/2009-08-31-LSDA-Name.ll
    llvm/trunk/test/DebugInfo/ARM/prologue_end.ll

Modified: llvm/trunk/lib/CodeGen/AsmPrinter/DwarfCFIException.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/AsmPrinter/DwarfCFIException.cpp?rev=275614&r1=275613&r2=275614&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/AsmPrinter/DwarfCFIException.cpp (original)
+++ llvm/trunk/lib/CodeGen/AsmPrinter/DwarfCFIException.cpp Fri Jul 15 16:10:29 2016
@@ -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(co
   shouldEmitLSDA = shouldEmitPersonality &&
     LSDAEncoding != dwarf::DW_EH_PE_omit;
 
-  shouldEmitCFI = shouldEmitPersonality || shouldEmitMoves;
+  shouldEmitCFI = MF->getMMI().getContext().getAsmInfo()->usesCFIForEH() &&
+                  (shouldEmitPersonality || shouldEmitMoves);
   beginFragment(&*MF->begin(), getExceptionSym);
 }
 

Modified: llvm/trunk/test/CodeGen/ARM/2009-08-31-LSDA-Name.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/ARM/2009-08-31-LSDA-Name.ll?rev=275614&r1=275613&r2=275614&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/ARM/2009-08-31-LSDA-Name.ll (original)
+++ llvm/trunk/test/CodeGen/ARM/2009-08-31-LSDA-Name.ll Fri Jul 15 16:10:29 2016
@@ -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* }

Modified: llvm/trunk/test/DebugInfo/ARM/prologue_end.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/DebugInfo/ARM/prologue_end.ll?rev=275614&r1=275613&r2=275614&view=diff
==============================================================================
--- llvm/trunk/test/DebugInfo/ARM/prologue_end.ll (original)
+++ llvm/trunk/test/DebugInfo/ARM/prologue_end.ll Fri Jul 15 16:10:29 2016
@@ -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