[clang-tools-extra] [clang] [llvm] [HLSL] Vector standard conversions (PR #71098)

[John McCall via cfe-commits]

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@@ -2414,9 +2420,41 @@ Value *ScalarExprEmitter::VisitCastExpr(CastExpr *CE) {
     return EmitScalarConversion(Visit(E), E->getType(), DestTy,
                                 CE->getExprLoc(), Opts);
   }
-  case CK_IntegralToFloating:
-  case CK_FloatingToIntegral:
-  case CK_FloatingCast:
+  case CK_IntegralToFloating: {
+    if (E->getType()->isExtVectorType() && DestTy->isExtVectorType()) {
+      QualType SrcElTy = E->getType()->castAs<VectorType>()->getElementType();
+      if (SrcElTy->isSignedIntegerOrEnumerationType())
+        return Builder.CreateSIToFP(Visit(E), ConvertType(DestTy), "conv");
+      return Builder.CreateUIToFP(Visit(E), ConvertType(DestTy), "conv");
+    }
+    CodeGenFunction::CGFPOptionsRAII FPOptsRAII(CGF, CE);
+    return EmitScalarConversion(Visit(E), E->getType(), DestTy,
+                                CE->getExprLoc());
+  }
+  case CK_FloatingToIntegral: {
+    if (E->getType()->isExtVectorType() && DestTy->isExtVectorType()) {
+      QualType DstElTy = DestTy->castAs<VectorType>()->getElementType();
+      if (DstElTy->isSignedIntegerOrEnumerationType())
+        return Builder.CreateFPToSI(Visit(E), ConvertType(DestTy), "conv");
+      return Builder.CreateFPToUI(Visit(E), ConvertType(DestTy), "conv");
+    }
+    CodeGenFunction::CGFPOptionsRAII FPOptsRAII(CGF, CE);
+    return EmitScalarConversion(Visit(E), E->getType(), DestTy,
+                                CE->getExprLoc());
+  }
+  case CK_FloatingCast: {
+    if (E->getType()->isExtVectorType() && DestTy->isExtVectorType()) {
+      QualType SrcElTy = E->getType()->castAs<VectorType>()->getElementType();
+      QualType DstElTy = DestTy->castAs<VectorType>()->getElementType();
+      if (DstElTy->castAs<BuiltinType>()->getKind() <
+          SrcElTy->castAs<BuiltinType>()->getKind())
+        return Builder.CreateFPTrunc(Visit(E), ConvertType(DestTy), "conv");
+      return Builder.CreateFPExt(Visit(E), ConvertType(DestTy), "conv");
+    }
+    CodeGenFunction::CGFPOptionsRAII FPOptsRAII(CGF, CE);
+    return EmitScalarConversion(Visit(E), E->getType(), DestTy,
+                                CE->getExprLoc());
+  }
----------------
rjmccall wrote:

Interesting.  I guess we would've had a miscompile here except that Sema currently never emits these cast kinds for vector types?

Given that, I feel like this code shouldn't check for `ExtVectorType` specifically.  If Sema in its wisdom tells us to emit one of these conversions, we should do it the right way for any vector type.

I guess HLSL probably doesn't care about any of the contextual things from the FP options.  Do the constrained FP intrinsics even support vectors?  Please at least leave a TODO about handling these properly.

https://github.com/llvm/llvm-project/pull/71098