[clang] [clang][ExprConst] Move vector diagnostics to checkBitCastConstexprEl… (PR #119366)

[Timm Baeder via cfe-commits]

https://github.com/tbaederr created https://github.com/llvm/llvm-project/pull/119366

…igibilityType

This is the function we use to diagnose invalid types, so use it for those checks as well.

>From 3fd250e95d6cca9bd822d516d5f6f862215dbe85 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Timm=20B=C3=A4der?= <tbaeder at redhat.com>
Date: Tue, 10 Dec 2024 13:08:39 +0100
Subject: [PATCH] [clang][ExprConst] Move vector diagnostics to
 checkBitCastConstexprEligibilityType

This is the function we use to diagnose invalid types, so use it for
those checks as well.
---
 clang/lib/AST/ExprConstant.cpp | 75 +++++++++++++---------------------
 1 file changed, 28 insertions(+), 47 deletions(-)

diff --git a/clang/lib/AST/ExprConstant.cpp b/clang/lib/AST/ExprConstant.cpp
index eed277deb4ac16..0ca92c36380f81 100644
--- a/clang/lib/AST/ExprConstant.cpp
+++ b/clang/lib/AST/ExprConstant.cpp
@@ -7352,31 +7352,6 @@ class APValueToBufferConverter {
     const VectorType *VTy = Ty->castAs<VectorType>();
     QualType EltTy = VTy->getElementType();
     unsigned NElts = VTy->getNumElements();
-    unsigned EltSize =
-        VTy->isExtVectorBoolType() ? 1 : Info.Ctx.getTypeSize(EltTy);
-
-    if ((NElts * EltSize) % Info.Ctx.getCharWidth() != 0) {
-      // The vector's size in bits is not a multiple of the target's byte size,
-      // so its layout is unspecified. For now, we'll simply treat these cases
-      // as unsupported (this should only be possible with OpenCL bool vectors
-      // whose element count isn't a multiple of the byte size).
-      Info.FFDiag(BCE->getBeginLoc(),
-                  diag::note_constexpr_bit_cast_invalid_vector)
-          << Ty.getCanonicalType() << EltSize << NElts
-          << Info.Ctx.getCharWidth();
-      return false;
-    }
-
-    if (EltTy->isRealFloatingType() && &Info.Ctx.getFloatTypeSemantics(EltTy) ==
-                                           &APFloat::x87DoubleExtended()) {
-      // The layout for x86_fp80 vectors seems to be handled very inconsistently
-      // by both clang and LLVM, so for now we won't allow bit_casts involving
-      // it in a constexpr context.
-      Info.FFDiag(BCE->getBeginLoc(),
-                  diag::note_constexpr_bit_cast_unsupported_type)
-          << EltTy;
-      return false;
-    }
 
     if (VTy->isExtVectorBoolType()) {
       // Special handling for OpenCL bool vectors:
@@ -7643,28 +7618,6 @@ class BufferToAPValueConverter {
     unsigned EltSize =
         VTy->isExtVectorBoolType() ? 1 : Info.Ctx.getTypeSize(EltTy);
 
-    if ((NElts * EltSize) % Info.Ctx.getCharWidth() != 0) {
-      // The vector's size in bits is not a multiple of the target's byte size,
-      // so its layout is unspecified. For now, we'll simply treat these cases
-      // as unsupported (this should only be possible with OpenCL bool vectors
-      // whose element count isn't a multiple of the byte size).
-      Info.FFDiag(BCE->getBeginLoc(),
-                  diag::note_constexpr_bit_cast_invalid_vector)
-          << QualType(VTy, 0) << EltSize << NElts << Info.Ctx.getCharWidth();
-      return std::nullopt;
-    }
-
-    if (EltTy->isRealFloatingType() && &Info.Ctx.getFloatTypeSemantics(EltTy) ==
-                                           &APFloat::x87DoubleExtended()) {
-      // The layout for x86_fp80 vectors seems to be handled very inconsistently
-      // by both clang and LLVM, so for now we won't allow bit_casts involving
-      // it in a constexpr context.
-      Info.FFDiag(BCE->getBeginLoc(),
-                  diag::note_constexpr_bit_cast_unsupported_type)
-          << EltTy;
-      return std::nullopt;
-    }
-
     SmallVector<APValue, 4> Elts;
     Elts.reserve(NElts);
     if (VTy->isExtVectorBoolType()) {
@@ -7793,6 +7746,34 @@ static bool checkBitCastConstexprEligibilityType(SourceLocation Loc,
                                             Info, Ctx, CheckingDest))
     return false;
 
+  if (const auto *VTy = Ty->getAs<VectorType>()) {
+    QualType EltTy = VTy->getElementType();
+    unsigned NElts = VTy->getNumElements();
+    unsigned EltSize =
+        VTy->isExtVectorBoolType() ? 1 : Info->Ctx.getTypeSize(EltTy);
+
+    if ((NElts * EltSize) % Info->Ctx.getCharWidth() != 0) {
+      // The vector's size in bits is not a multiple of the target's byte size,
+      // so its layout is unspecified. For now, we'll simply treat these cases
+      // as unsupported (this should only be possible with OpenCL bool vectors
+      // whose element count isn't a multiple of the byte size).
+      Info->FFDiag(Loc, diag::note_constexpr_bit_cast_invalid_vector)
+          << QualType(VTy, 0) << EltSize << NElts << Info->Ctx.getCharWidth();
+      return false;
+    }
+
+    if (EltTy->isRealFloatingType() &&
+        &Info->Ctx.getFloatTypeSemantics(EltTy) ==
+            &APFloat::x87DoubleExtended()) {
+      // The layout for x86_fp80 vectors seems to be handled very inconsistently
+      // by both clang and LLVM, so for now we won't allow bit_casts involving
+      // it in a constexpr context.
+      Info->FFDiag(Loc, diag::note_constexpr_bit_cast_unsupported_type)
+          << EltTy;
+      return false;
+    }
+  }
+
   return true;
 }