From 1b104388752f66191c867380efde7bbf1f13ca80 Mon Sep 17 00:00:00 2001
From: Bill Wendling <isanbard@gmail.com>
Date: Fri, 9 Aug 2019 20:16:31 +0000
Subject: [MC] Don't recreate a label if it's already used

Summary:
This patch keeps track of MCSymbols created for blocks that were
referenced in inline asm. It prevents creating a new symbol which
doesn't refer to the block.

Inline asm may have a reference to a label. The asm parser however
doesn't recognize it as a label and tries to create a new symbol. The
result being that instead of the original symbol (e.g. ".Ltmp0") the
parser replaces it in the inline asm with the new one (e.g. ".Ltmp00")
without updating it in the symbol table. So the machine basic block
retains the "old" symbol (".Ltmp0"), but the inline asm uses the new one
(".Ltmp00").

Reviewers: nickdesaulniers, craig.topper

Subscribers: nathanchance, javed.absar, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D65304

llvm-svn: 368477
---
 llvm/lib/MC/MCContext.cpp | 6 ++++++
 1 file changed, 6 insertions(+)

(limited to 'llvm/lib/MC/MCContext.cpp')

diff --git a/llvm/lib/MC/MCContext.cpp b/llvm/lib/MC/MCContext.cpp
index a030f5e4eb0..6975ab3af53 100644
--- a/llvm/lib/MC/MCContext.cpp
+++ b/llvm/lib/MC/MCContext.cpp
@@ -61,6 +61,7 @@ MCContext::MCContext(const MCAsmInfo *mai, const MCRegisterInfo *mri,
                      MCTargetOptions const *TargetOpts, bool DoAutoReset)
     : SrcMgr(mgr), InlineSrcMgr(nullptr), MAI(mai), MRI(mri), MOFI(mofi),
       Symbols(Allocator), UsedNames(Allocator),
+      InlineAsmUsedLabelNames(Allocator),
       CurrentDwarfLoc(0, 0, 0, DWARF2_FLAG_IS_STMT, 0, 0),
       AutoReset(DoAutoReset), TargetOptions(TargetOpts) {
   SecureLogFile = AsSecureLogFileName;
@@ -90,6 +91,7 @@ void MCContext::reset() {
   XCOFFAllocator.DestroyAll();
 
   MCSubtargetAllocator.DestroyAll();
+  InlineAsmUsedLabelNames.clear();
   UsedNames.clear();
   Symbols.clear();
   Allocator.Reset();
@@ -272,6 +274,10 @@ void MCContext::setSymbolValue(MCStreamer &Streamer,
   Streamer.EmitAssignment(Symbol, MCConstantExpr::create(Val, *this));
 }
 
+void MCContext::registerInlineAsmLabel(MCSymbol *Sym) {
+  InlineAsmUsedLabelNames[Sym->getName()] = Sym;
+}
+
 //===----------------------------------------------------------------------===//
 // Section Management
 //===----------------------------------------------------------------------===//
-- 
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