am 1c4ad5ef: Merge branch \'upstream\' into merge-2012_09_10

* commit '1c4ad5ef4fab105f0c8af7edd026e00502fb6279': (446 commits)
  Revert r163556. Missed updates to tablegen files.
  Update function names to conform to guidelines.  No functional change intended.
  test/CodeGen/X86/ms-inline-asm.ll: Relax for non-darwin x86 targets. '##InlineAsm' could not be seen in other hosts.
  [ms-inline asm] Properly emit the asm directives when the AsmPrinterVariant and InlineAsmVariant don't match.
  Update test case for Release builds.
  Remove redundant semicolons which are null statements.
  Disable stack coloring because it makes dragonegg fail bootstrapping.
  [ms-inline asm] Pass the correct AsmVariant to the PrintAsmOperand() function and update the printOperand() function accordingly.
  [ms-inline asm] Add support for .att_syntax directive.
  Enable stack coloring.
  Don't attempt to use flags from predicated instructions.
  [Object] Extract Elf_Ehdr. Patch by Hemant Kulkarni!
  Stack Coloring: Handle the case where END markers come before BEGIN markers properly.
  Enhance PR11334 fix to support extload from v2f32/v4f32
  Add "blocked" heuristic to the Hexagon MI scheduler.
  Fold multiply by 0 or 1 when in UnsafeFPMath mode in SelectionDAG::getNode().
  whitespace
  Add boolean simplification support from CMOV
  Fix an assertion failure when optimising a shufflevector incorrectly into concat_vectors, and a followup bug with SelectionDAG::getNode() creating nodes with invalid types.
  Minor cleanup. No functional change.
  ...

1 files changed, 31 insertions, 8 deletions

diff --git a/lib/Transforms/Scalar/LICM.cpp b/lib/Transforms/Scalar/LICM.cpp
index 0192e92..99bedce 100644
--- a/lib/Transforms/Scalar/LICM.cpp
+++ b/lib/Transforms/Scalar/LICM.cpp
@@ -108,6 +108,9 @@ namespace {
     BasicBlock *Preheader;   // The preheader block of the current loop...
     Loop *CurLoop;           // The current loop we are working on...
     AliasSetTracker *CurAST; // AliasSet information for the current loop...
+    bool MayThrow;           // The current loop contains an instruction which
+                             // may throw, thus preventing code motion of
+                             // instructions with side effects.
     DenseMap<Loop*, AliasSetTracker*> LoopToAliasSetMap;
 
     /// cloneBasicBlockAnalysis - Simple Analysis hook. Clone alias set info.
@@ -240,6 +243,15 @@ bool LICM::runOnLoop(Loop *L, LPPassManager &LPM) {
       CurAST->add(*BB);                 // Incorporate the specified basic block
   }
 
+  MayThrow = false;
+  // TODO: We've already searched for instructions which may throw in subloops.
+  // We may want to reuse this information.
+  for (Loop::block_iterator BB = L->block_begin(), BBE = L->block_end();
+       (BB != BBE) && !MayThrow ; ++BB)
+    for (BasicBlock::iterator I = (*BB)->begin(), E = (*BB)->end();
+         (I != E) && !MayThrow; ++I)
+      MayThrow |= I->mayThrow();
+
   // We want to visit all of the instructions in this loop... that are not parts
   // of our subloops (they have already had their invariants hoisted out of
   // their loop, into this loop, so there is no need to process the BODIES of
@@ -307,7 +319,7 @@ void LICM::SinkRegion(DomTreeNode *N) {
 
     // If the instruction is dead, we would try to sink it because it isn't used
     // in the loop, instead, just delete it.
-    if (isInstructionTriviallyDead(&I)) {
+    if (isInstructionTriviallyDead(&I, TLI)) {
       DEBUG(dbgs() << "LICM deleting dead inst: " << I << '\n');
       ++II;
       CurAST->deleteValue(&I);
@@ -418,17 +430,22 @@ bool LICM::canSinkOrHoistInst(Instruction &I) {
       if (!FoundMod) return true;
     }
 
-    // FIXME: This should use mod/ref information to see if we can hoist or sink
-    // the call.
+    // FIXME: This should use mod/ref information to see if we can hoist or
+    // sink the call.
 
     return false;
   }
 
-  // Otherwise these instructions are hoistable/sinkable
-  return isa<BinaryOperator>(I) || isa<CastInst>(I) ||
-         isa<SelectInst>(I) || isa<GetElementPtrInst>(I) || isa<CmpInst>(I) ||
-         isa<InsertElementInst>(I) || isa<ExtractElementInst>(I) ||
-         isa<ShuffleVectorInst>(I);
+  // Only these instructions are hoistable/sinkable.
+  bool HoistableKind = (isa<BinaryOperator>(I) || isa<CastInst>(I) ||
+                            isa<SelectInst>(I) || isa<GetElementPtrInst>(I) ||
+                            isa<CmpInst>(I)    || isa<InsertElementInst>(I) ||
+                            isa<ExtractElementInst>(I) ||
+                            isa<ShuffleVectorInst>(I));
+  if (!HoistableKind)
+      return false;
+
+  return isSafeToExecuteUnconditionally(I);
 }
 
 /// isNotUsedInLoop - Return true if the only users of this instruction are
@@ -604,6 +621,12 @@ bool LICM::isSafeToExecuteUnconditionally(Instruction &Inst) {
 }
 
 bool LICM::isGuaranteedToExecute(Instruction &Inst) {
+
+  // Somewhere in this loop there is an instruction which may throw and make us
+  // exit the loop.
+  if (MayThrow)
+    return false;
+
   // Otherwise we have to check to make sure that the instruction dominates all
   // of the exit blocks.  If it doesn't, then there is a path out of the loop
   // which does not execute this instruction, so we can't hoist it.