MFC r318655:

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

  [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

3 files changed, 15 insertions, 0 deletions

diff --git a/contrib/llvm/include/llvm/MC/ConstantPools.h b/contrib/llvm/include/llvm/MC/ConstantPools.h
index f0c445d..3925800 100644
--- a/contrib/llvm/include/llvm/MC/ConstantPools.h
+++ b/contrib/llvm/include/llvm/MC/ConstantPools.h
@@ -60,6 +60,8 @@ public:
 
   // 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);
 
diff --git a/contrib/llvm/lib/MC/ConstantPools.cpp b/contrib/llvm/lib/MC/ConstantPools.cpp
index 9608c2c..bf2c39e 100644
--- a/contrib/llvm/lib/MC/ConstantPools.cpp
+++ b/contrib/llvm/lib/MC/ConstantPools.cpp
@@ -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) {
diff --git a/contrib/llvm/lib/Target/ARM/MCTargetDesc/ARMTargetStreamer.cpp b/contrib/llvm/lib/Target/ARM/MCTargetDesc/ARMTargetStreamer.cpp
index c0d10c8..e49f1a3 100644
--- a/contrib/llvm/lib/Target/ARM/MCTargetDesc/ARMTargetStreamer.cpp
+++ b/contrib/llvm/lib/Target/ARM/MCTargetDesc/ARMTargetStreamer.cpp
@@ -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.