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

2 files changed, 10 insertions, 2 deletions

diff --git a/llvm/lib/Transforms/IPO/DeadArgumentElimination.cpp b/llvm/lib/Transforms/IPO/DeadArgumentElimination.cpp
index 47df235424e..e8b168e4575 100644
--- a/llvm/lib/Transforms/IPO/DeadArgumentElimination.cpp
+++ b/llvm/lib/Transforms/IPO/DeadArgumentElimination.cpp
@@ -791,7 +791,8 @@ bool DAE::RemoveDeadStuffFromFunction(Function *F) {
       } else if (New->getType()->isVoidTy()) {
         // Our return value has uses, but they will get removed later on.
         // Replace by null for now.
-        Call->replaceAllUsesWith(Constant::getNullValue(Call->getType()));
+        if (!Call->getType()->isX86_MMXTy())
+          Call->replaceAllUsesWith(Constant::getNullValue(Call->getType()));
       } else {
         assert(RetTy->isStructTy() &&
                "Return type changed, but not into a void. The old return type"
@@ -854,7 +855,8 @@ bool DAE::RemoveDeadStuffFromFunction(Function *F) {
     } else {
       // If this argument is dead, replace any uses of it with null constants
       // (these are guaranteed to become unused later on).
-      I->replaceAllUsesWith(Constant::getNullValue(I->getType()));
+      if (!I->getType()->isX86_MMXTy())
+        I->replaceAllUsesWith(Constant::getNullValue(I->getType()));
     }
 
   // If we change the return value of the function we must rewrite any return
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;
     }