[clang] [llvm] Diagnose invalid fixed point conversion (PR #80763)

[via llvm-commits]

https://github.com/PiJoules created https://github.com/llvm/llvm-project/pull/80763

None

>From faf74616efab09e59aade180ce44b68e04259e0e Mon Sep 17 00:00:00 2001
From: Leonard Chan <leonardchan at google.com>
Date: Mon, 5 Feb 2024 14:55:34 -0800
Subject: [PATCH 1/2] [llvm] Fix assertion error where we didn't check fixed
 point types.

---
 llvm/lib/CodeGen/AsmPrinter/DebugHandlerBase.cpp | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/llvm/lib/CodeGen/AsmPrinter/DebugHandlerBase.cpp b/llvm/lib/CodeGen/AsmPrinter/DebugHandlerBase.cpp
index eb2d992c7e75e..f00ff1565c665 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DebugHandlerBase.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DebugHandlerBase.cpp
@@ -224,12 +224,15 @@ bool DebugHandlerBase::isUnsignedDIType(const DIType *Ty) {
           Encoding == dwarf::DW_ATE_float || Encoding == dwarf::DW_ATE_UTF ||
           Encoding == dwarf::DW_ATE_boolean ||
           Encoding == dwarf::DW_ATE_complex_float ||
+          Encoding == dwarf::DW_ATE_signed_fixed ||
+          Encoding == dwarf::DW_ATE_unsigned_fixed ||
           (Ty->getTag() == dwarf::DW_TAG_unspecified_type &&
            Ty->getName() == "decltype(nullptr)")) &&
          "Unsupported encoding");
   return Encoding == dwarf::DW_ATE_unsigned ||
          Encoding == dwarf::DW_ATE_unsigned_char ||
          Encoding == dwarf::DW_ATE_UTF || Encoding == dwarf::DW_ATE_boolean ||
+         Encoding == llvm::dwarf::DW_ATE_unsigned_fixed ||
          Ty->getTag() == dwarf::DW_TAG_unspecified_type;
 }
 

>From 9c8af35404e5f8f4737be1fc725000cf0c3d52f1 Mon Sep 17 00:00:00 2001
From: Leonard Chan <leonardchan at google.com>
Date: Mon, 5 Feb 2024 15:33:09 -0800
Subject: [PATCH 2/2] [Clang] Diagnose improper fixed point conversions in C++

---
 clang/include/clang/AST/Type.h             | 7 +++++++
 clang/lib/Sema/SemaOverload.cpp            | 5 ++++-
 clang/test/Frontend/fixed_point_errors.cpp | 4 ++++
 3 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/clang/include/clang/AST/Type.h b/clang/include/clang/AST/Type.h
index d6a55f39a4bed..1942b0e67f65a 100644
--- a/clang/include/clang/AST/Type.h
+++ b/clang/include/clang/AST/Type.h
@@ -2613,6 +2613,9 @@ class alignas(TypeAlignment) Type : public ExtQualsTypeCommonBase {
   /// Return true if this is a fixed point or integer type.
   bool isFixedPointOrIntegerType() const;
 
+  /// Return true if this can be converted to (or from) a fixed point type.
+  bool isConvertibleToFixedPointType() const;
+
   /// Return true if this is a saturated fixed point type according to
   /// ISO/IEC JTC1 SC22 WG14 N1169. This type can be signed or unsigned.
   bool isSaturatedFixedPointType() const;
@@ -7493,6 +7496,10 @@ inline bool Type::isFixedPointOrIntegerType() const {
   return isFixedPointType() || isIntegerType();
 }
 
+inline bool Type::isConvertibleToFixedPointType() const {
+  return isRealFloatingType() || isFixedPointOrIntegerType();
+}
+
 inline bool Type::isSaturatedFixedPointType() const {
   if (const auto *BT = dyn_cast<BuiltinType>(CanonicalType)) {
     return BT->getKind() >= BuiltinType::SatShortAccum &&
diff --git a/clang/lib/Sema/SemaOverload.cpp b/clang/lib/Sema/SemaOverload.cpp
index 940bcccb9e261..5fdaf15eaf342 100644
--- a/clang/lib/Sema/SemaOverload.cpp
+++ b/clang/lib/Sema/SemaOverload.cpp
@@ -2177,7 +2177,10 @@ static bool IsStandardConversion(Sema &S, Expr* From, QualType ToType,
              From->isIntegerConstantExpr(S.getASTContext())) {
     SCS.Second = ICK_Compatible_Conversion;
     FromType = ToType;
-  } else if (ToType->isFixedPointType() || FromType->isFixedPointType()) {
+  } else if ((ToType->isFixedPointType() &&
+              FromType->isConvertibleToFixedPointType()) ||
+             (FromType->isFixedPointType() &&
+              ToType->isConvertibleToFixedPointType())) {
     SCS.Second = ICK_Fixed_Point_Conversion;
     FromType = ToType;
   } else {
diff --git a/clang/test/Frontend/fixed_point_errors.cpp b/clang/test/Frontend/fixed_point_errors.cpp
index 4097cd73c8450..ef064bc38873d 100644
--- a/clang/test/Frontend/fixed_point_errors.cpp
+++ b/clang/test/Frontend/fixed_point_errors.cpp
@@ -14,3 +14,7 @@ int fract_int = 10r;     // expected-error{{invalid suffix 'r' on integer consta
 float accum_flt = 0.0k;  // expected-error{{invalid suffix 'k' on floating constant}}
 float fract_flt = 0.0r;  // expected-error{{invalid suffix 'r' on floating constant}}
 #endif
+
+#ifndef WITHOUT_FIXED_POINT
+const char *c = 10.0k;  // expected-error{{cannot initialize a variable of type 'const char *' with an rvalue of type '_Accum'}}
+#endif