[clang] [HLSL] Cleanup TargetInfo handling (PR #90694)

[Chris B via cfe-commits]

https://github.com/llvm-beanz updated https://github.com/llvm/llvm-project/pull/90694

>From 2464bcb75b047c49076f0718470f27a561252a62 Mon Sep 17 00:00:00 2001
From: Chris Bieneman <chris.bieneman at me.com>
Date: Tue, 30 Apr 2024 20:49:35 -0500
Subject: [PATCH 1/2] [NFC][HLSL] Cleanup TargetInfo handling

We had some odd places where we set target behaviors. We were setting
the long size in target-specific code, but it should be language-based.
We were not setting the Half float type semantics correctly, and instead
were overriding the query in the AST context.

This change is NFC, but it moves existing code to the right places in
the Target so that as we continue working on target and language feature
they are controlled in the right places.
---
 clang/lib/AST/ASTContext.cpp      | 10 +---------
 clang/lib/Basic/TargetInfo.cpp    | 10 ++++++++++
 clang/lib/Basic/Targets/DirectX.h |  1 -
 3 files changed, 11 insertions(+), 10 deletions(-)

diff --git a/clang/lib/AST/ASTContext.cpp b/clang/lib/AST/ASTContext.cpp
index cbf4932aff9a6b..565870eba7014f 100644
--- a/clang/lib/AST/ASTContext.cpp
+++ b/clang/lib/AST/ASTContext.cpp
@@ -1612,15 +1612,7 @@ const llvm::fltSemantics &ASTContext::getFloatTypeSemantics(QualType T) const {
   case BuiltinType::Float16:
     return Target->getHalfFormat();
   case BuiltinType::Half:
-    // For HLSL, when the native half type is disabled, half will be treat as
-    // float.
-    if (getLangOpts().HLSL)
-      if (getLangOpts().NativeHalfType)
-        return Target->getHalfFormat();
-      else
-        return Target->getFloatFormat();
-    else
-      return Target->getHalfFormat();
+    return Target->getHalfFormat();
   case BuiltinType::Float:      return Target->getFloatFormat();
   case BuiltinType::Double:     return Target->getDoubleFormat();
   case BuiltinType::Ibm128:
diff --git a/clang/lib/Basic/TargetInfo.cpp b/clang/lib/Basic/TargetInfo.cpp
index f96956f31d50dc..29f5cd14e46e11 100644
--- a/clang/lib/Basic/TargetInfo.cpp
+++ b/clang/lib/Basic/TargetInfo.cpp
@@ -406,6 +406,16 @@ void TargetInfo::adjust(DiagnosticsEngine &Diags, LangOptions &Opts) {
     LongDoubleAlign = 64;
   }
 
+  // HLSL explicitly defines the sizes and formats of some data types, and we
+  // need to conform to those regardless of what architecture you are targeting.
+  if (Opts.HLSL) {
+    LongWidth = LongAlign = 64;
+    if (!Opts.NativeHalfType) {
+      HalfFormat = &llvm::APFloat::IEEEsingle();
+      HalfWidth = HalfAlign = 32;
+    }
+  }
+
   if (Opts.OpenCL) {
     // OpenCL C requires specific widths for types, irrespective of
     // what these normally are for the target.
diff --git a/clang/lib/Basic/Targets/DirectX.h b/clang/lib/Basic/Targets/DirectX.h
index acfcc8c47ba950..a084e2823453fc 100644
--- a/clang/lib/Basic/Targets/DirectX.h
+++ b/clang/lib/Basic/Targets/DirectX.h
@@ -53,7 +53,6 @@ class LLVM_LIBRARY_VISIBILITY DirectXTargetInfo : public TargetInfo {
       : TargetInfo(Triple) {
     TLSSupported = false;
     VLASupported = false;
-    LongWidth = LongAlign = 64;
     AddrSpaceMap = &DirectXAddrSpaceMap;
     UseAddrSpaceMapMangling = true;
     HasLegalHalfType = true;

>From 330151395257f44a8936080f9e994ab61a0c38ae Mon Sep 17 00:00:00 2001
From: Chris Bieneman <chris.bieneman at me.com>
Date: Wed, 1 May 2024 12:02:24 -0500
Subject: [PATCH 2/2] Add test for sizeof(half)

---
 clang/test/SemaHLSL/Types/Arithmetic/half_size.hlsl | 11 +++++++++++
 1 file changed, 11 insertions(+)
 create mode 100644 clang/test/SemaHLSL/Types/Arithmetic/half_size.hlsl

diff --git a/clang/test/SemaHLSL/Types/Arithmetic/half_size.hlsl b/clang/test/SemaHLSL/Types/Arithmetic/half_size.hlsl
new file mode 100644
index 00000000000000..7de46746999304
--- /dev/null
+++ b/clang/test/SemaHLSL/Types/Arithmetic/half_size.hlsl
@@ -0,0 +1,11 @@
+// RUN: %clang_cc1 -triple dxil-pc-shadermodel6.4-library -verify %s
+// RUN: %clang_cc1 -triple dxil-pc-shadermodel6.4-library -verify -fnative-half-type %s
+// RUN: %clang_cc1 -triple spirv-linux-vulkan-library -verify %s
+// RUN: %clang_cc1 -triple spirv-linux-vulkan-library -verify -fnative-half-type %s
+
+// expected-no-diagnostics
+#ifdef __HLSL_ENABLE_16_BIT
+_Static_assert(sizeof(half) == 2, "half is 2 bytes");
+#else
+_Static_assert(sizeof(half) == 4, "half is 4 bytes");
+#endif