While testing dragonegg I noticed that isCastable and getCastOpcode

had gotten out of sync: isCastable didn't think it was possible to
cast the x86_mmx type to anything, while it did think it possible
to cast an i64 to x86_mmx.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@128705 91177308-0d34-0410-b5e6-96231b3b80d8

lib/VMCore/Instructions.cpp

@@ -2297,8 +2297,12 @@ bool CastInst::isCastable(const Type *SrcTy, const Type *DestTy) {
     if (const VectorType *SrcPTy = dyn_cast<VectorType>(SrcTy)) {
                                                 // Casting from vector
       return DestPTy->getBitWidth() == SrcPTy->getBitWidth();
-    } else {                                    // Casting from something else
-      return DestPTy->getBitWidth() == SrcBits;
+    } else if (DestPTy->getBitWidth() == SrcBits) {
+      return true;                              // float/int -> vector
+    } else if (SrcTy->isX86_MMXTy()) {
+      return DestPTy->getBitWidth() == 64;      // MMX to 64-bit vector
+    } else {
+      return false;
     }
   } else if (DestTy->isPointerTy()) {        // Casting to pointer
     if (SrcTy->isPointerTy()) {              // Casting from pointer
@@ -2308,8 +2312,12 @@ bool CastInst::isCastable(const Type *SrcTy, const Type *DestTy) {
     } else {                                    // Casting from something else
       return false;
     }
-  } else if (DestTy->isX86_MMXTy()) {     
-    return SrcBits == 64;
+  } else if (DestTy->isX86_MMXTy()) {
+    if (const VectorType *SrcPTy = dyn_cast<VectorType>(SrcTy)) {
+      return SrcPTy->getBitWidth() == 64;       // 64-bit vector to MMX
+    } else {
+      return false;
+    }
   } else {                                      // Casting to something else
     return false;
   }

unittests/VMCore/InstructionsTest.cpp

@@ -107,5 +107,18 @@ TEST(InstructionsTest, BranchInst) {
   delete bb1;
 }
 
+TEST(InstructionsTest, CastInst) {
+  LLVMContext &C(getGlobalContext());
+
+  const Type* Int8Ty = Type::getInt8Ty(C);
+  const Type* Int64Ty = Type::getInt64Ty(C);
+  const Type* V8x8Ty = VectorType::get(Int8Ty, 8);
+  const Type* X86MMXTy = Type::getX86_MMXTy(C);
+
+  EXPECT_TRUE(CastInst::isCastable(V8x8Ty, X86MMXTy));
+  EXPECT_TRUE(CastInst::isCastable(X86MMXTy, V8x8Ty));
+  EXPECT_FALSE(CastInst::isCastable(Int64Ty, X86MMXTy));
+}
+
 }  // end anonymous namespace
 }  // end namespace llvm