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Pull in r302416 from upstream llvm trunk (by Martin Storsjö):

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[ARM] Clear the constant pool cache on explicit .ltorg directives

  Multiple ldr pseudoinstructions with the same constant value will
  reuse the same constant pool entry. However, if the constant pool is
  explicitly flushed with a .ltorg directive, we should not try to
  reference constants in the previous pool any longer, since they may
  be out of range.

  This fixes assembling hand-written assembler source which repeatedly
  loads the same constant value, across a binary size larger than the
  pc-relative fixup range for ldr instructions (4096 bytes). Such
  assembler source already uses explicit .ltorg instructions to emit
  constant pools with regular intervals. However if we try to reuse
  constants emitted in earlier pools, they end up out of range.

  This makes the output of the testcase match what binutils gas does
  (prior to this patch, it would fail to assemble).

  Differential Revision: https://reviews.llvm.org/D32847

This should fix "out of range pc-relative fixup value" errors, when
compiling certain ARM inline assembly for www/webkit-gtk[23].

Reported by:	mmel
MFC after:	3 days
This commit is contained in:
dim 2017-05-22 16:16:48 +00:00
parent b9ab25c19f
commit 25ba95ba2f
3 changed files with 15 additions and 0 deletions
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3
contrib/llvm/include/llvm/MC/ConstantPools.h
View File

@ -60,6 +60,8 @@ class ConstantPool {
// Return true if the constant pool is empty
bool empty();
void clearCache();
};
class AssemblerConstantPools {
@ -83,6 +85,7 @@ class AssemblerConstantPools {
public:
void emitAll(MCStreamer &Streamer);
void emitForCurrentSection(MCStreamer &Streamer);
void clearCacheForCurrentSection(MCStreamer &Streamer);
const MCExpr *addEntry(MCStreamer &Streamer, const MCExpr *Expr,
unsigned Size, SMLoc Loc);

11
contrib/llvm/lib/MC/ConstantPools.cpp
View File

@ -54,6 +54,10 @@ const MCExpr *ConstantPool::addEntry(const MCExpr *Value, MCContext &Context,
bool ConstantPool::empty() { return Entries.empty(); }
void ConstantPool::clearCache() {
CachedEntries.clear();
}
//
// AssemblerConstantPools implementation
//
@ -95,6 +99,13 @@ void AssemblerConstantPools::emitForCurrentSection(MCStreamer &Streamer) {
}
}
void AssemblerConstantPools::clearCacheForCurrentSection(MCStreamer &Streamer) {
MCSection *Section = Streamer.getCurrentSectionOnly();
if (ConstantPool *CP = getConstantPool(Section)) {
CP->clearCache();
}
}
const MCExpr *AssemblerConstantPools::addEntry(MCStreamer &Streamer,
const MCExpr *Expr,
unsigned Size, SMLoc Loc) {

1
contrib/llvm/lib/Target/ARM/MCTargetDesc/ARMTargetStreamer.cpp
View File

@ -33,6 +33,7 @@ const MCExpr *ARMTargetStreamer::addConstantPoolEntry(const MCExpr *Expr, SMLoc
void ARMTargetStreamer::emitCurrentConstantPool() {
ConstantPools->emitForCurrentSection(Streamer);
ConstantPools->clearCacheForCurrentSection(Streamer);
}
// finish() - write out any non-empty assembler constant pools.