Pull in r248439 from upstream llvm trunk (by Sanjay Patel):

  set div/rem default values to 'expensive' in TargetTransformInfo's
  cost model

  ...because that's what the cost model was intended to do.

  As discussed in D12882, this fix has a temporary unintended
  consequence for SimplifyCFG: it causes us to not speculate an fdiv.
  However, two wrongs make PR24818 right, and two wrongs make PR24343
  act right even though it's really still wrong.

  I intend to correct SimplifyCFG and add to CodeGenPrepare to account
  for this cost model change and preserve the righteousness for the bug
  report cases.

  https://llvm.org/bugs/show_bug.cgi?id=24818
  https://llvm.org/bugs/show_bug.cgi?id=24343

  Differential Revision: http://reviews.llvm.org/D12882

This fixes the too-eager fdiv hoisting in pow(), which could lead to
unexpected floating point exceptions.

1 files changed, 8 insertions, 0 deletions

diff --git a/contrib/llvm/include/llvm/Analysis/TargetTransformInfoImpl.h b/contrib/llvm/include/llvm/Analysis/TargetTransformInfoImpl.h
index 035cb04..ecc7885 100644
--- a/contrib/llvm/include/llvm/Analysis/TargetTransformInfoImpl.h
+++ b/contrib/llvm/include/llvm/Analysis/TargetTransformInfoImpl.h
@@ -60,6 +60,14 @@ public:
       // Otherwise, the default basic cost is used.
       return TTI::TCC_Basic;
 
+    case Instruction::FDiv:
+    case Instruction::FRem:
+    case Instruction::SDiv:
+    case Instruction::SRem:
+    case Instruction::UDiv:
+    case Instruction::URem:
+      return TTI::TCC_Expensive;
+
     case Instruction::IntToPtr: {
       // An inttoptr cast is free so long as the input is a legal integer type
       // which doesn't contain values outside the range of a pointer.