Massive rewrite of MMX:

The x86_mmx type is used for MMX intrinsics, parameters and
return values where these use MMX registers, and is also
supported in load, store, and bitcast.

Only the above operations generate MMX instructions, and optimizations
do not operate on or produce MMX intrinsics. 

MMX-sized vectors <2 x i32> etc. are lowered to XMM or split into
smaller pieces.  Optimizations may occur on these forms and the
result casted back to x86_mmx, provided the result feeds into a
previous existing x86_mmx operation.

The point of all this is prevent optimizations from introducing
MMX operations, which is unsafe due to the EMMS problem.

llvm-svn: 115243

1 files changed, 6 insertions, 0 deletions

diff --git a/llvm/lib/Transforms/Scalar/ScalarReplAggregates.cpp b/llvm/lib/Transforms/Scalar/ScalarReplAggregates.cpp
index fee317dbd9a..33ecb5bf9bd 100644
--- a/llvm/lib/Transforms/Scalar/ScalarReplAggregates.cpp
+++ b/llvm/lib/Transforms/Scalar/ScalarReplAggregates.cpp
@@ -321,6 +321,9 @@ bool ConvertToScalarInfo::CanConvertToScalar(Value *V, uint64_t Offset) {
       // Don't break volatile loads.
       if (LI->isVolatile())
         return false;
+      // Don't touch MMX operations.
+      if (LI->getType()->isX86_MMXTy())
+        return false;
       MergeInType(LI->getType(), Offset);
       continue;
     }
@@ -328,6 +331,9 @@ bool ConvertToScalarInfo::CanConvertToScalar(Value *V, uint64_t Offset) {
     if (StoreInst *SI = dyn_cast<StoreInst>(User)) {
       // Storing the pointer, not into the value?
       if (SI->getOperand(0) == V || SI->isVolatile()) return false;
+      // Don't touch MMX operations.
+      if (SI->getOperand(0)->getType()->isX86_MMXTy())
+        return false;
       MergeInType(SI->getOperand(0)->getType(), Offset);
       continue;
     }