From 1083a5297a60aabaa949d42483d89355cfaf3219 Mon Sep 17 00:00:00 2001
From: Saleem Abdulrasool <compnerd@compnerd.org>
Date: Fri, 15 Jul 2016 21:10:29 +0000
Subject: [PATCH] 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.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@275614 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/CodeGen/AsmPrinter/DwarfCFIException.cpp | 9 +++++----
 test/CodeGen/ARM/2009-08-31-LSDA-Name.ll     | 8 +++++---
 test/DebugInfo/ARM/prologue_end.ll           | 1 -
 3 files changed, 10 insertions(+), 8 deletions(-)

diff --git a/lib/CodeGen/AsmPrinter/DwarfCFIException.cpp b/lib/CodeGen/AsmPrinter/DwarfCFIException.cpp
index 5cc063e6c95..2eae1b23447 100644
--- a/lib/CodeGen/AsmPrinter/DwarfCFIException.cpp
+++ b/lib/CodeGen/AsmPrinter/DwarfCFIException.cpp
@@ -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);
 }
 
diff --git a/test/CodeGen/ARM/2009-08-31-LSDA-Name.ll b/test/CodeGen/ARM/2009-08-31-LSDA-Name.ll
index d402c16ccac..0a9fd895574 100644
--- a/test/CodeGen/ARM/2009-08-31-LSDA-Name.ll
+++ b/test/CodeGen/ARM/2009-08-31-LSDA-Name.ll
@@ -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* }
diff --git a/test/DebugInfo/ARM/prologue_end.ll b/test/DebugInfo/ARM/prologue_end.ll
index 533d1c82554..43e3c51ecc7 100644
--- a/test/DebugInfo/ARM/prologue_end.ll
+++ b/test/DebugInfo/ARM/prologue_end.ll
@@ -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