https://github.com/Maetveis updated
https://github.com/llvm/llvm-project/pull/131477
From 66d0105572f7aba8c633d0d5cb5ff7cb8cf44408 Mon Sep 17 00:00:00 2001
From: Gergely Meszaros <meszaros.gergel...@gmail.com>
Date: Sat, 15 Mar 2025 22:37:07 +0100
Subject: [PATCH 1/2] [Clang][Sema] Fix -Whigher-precision-for-complex-division
- Fix false positive when divisor is a real number
- Fix false negative when divident is real, but divisor is complex
- Fix false negative when due to promotion the division is performed
in higher precision than the divident.
- Fix false negative in divide and assign (`a /= b`)
---
clang/lib/Sema/SemaExpr.cpp | 78 ++++++++++---------
.../Sema/complex-div-warn-higher-precision.c | 58 ++++++++++++++
2 files changed, 98 insertions(+), 38 deletions(-)
create mode 100644 clang/test/Sema/complex-div-warn-higher-precision.c
diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp
index e7f418ae6802e..5001df20afe03 100644
--- a/clang/lib/Sema/SemaExpr.cpp
+++ b/clang/lib/Sema/SemaExpr.cpp
@@ -10591,6 +10591,45 @@ static void checkArithmeticNull(Sema &S, ExprResult
&LHS, ExprResult &RHS,
<< LHS.get()->getSourceRange() << RHS.get()->getSourceRange();
}
+static void DetectPrecisionLossInComplexDivision(Sema &S, QualType DivisorTy,
+ SourceLocation OpLoc) {
+ // Either real/real or complex/real division.
+ // Either way there can be no precision loss.
+ auto *CT = DivisorTy->getAs<ComplexType>();
+ if (!CT)
+ return;
+
+ QualType ElementType = CT->getElementType();
+ bool IsComplexRangePromoted = S.getLangOpts().getComplexRange() ==
+ LangOptions::ComplexRangeKind::CX_Promoted;
+ if (!ElementType->isFloatingType() || !IsComplexRangePromoted)
+ return;
+
+ ASTContext &Ctx = S.getASTContext();
+ QualType HigherElementType = Ctx.GetHigherPrecisionFPType(ElementType);
+ const llvm::fltSemantics &ElementTypeSemantics =
+ Ctx.getFloatTypeSemantics(ElementType);
+ const llvm::fltSemantics &HigherElementTypeSemantics =
+ Ctx.getFloatTypeSemantics(HigherElementType);
+
+ if ((llvm::APFloat::semanticsMaxExponent(ElementTypeSemantics) * 2 + 1 >
+ llvm::APFloat::semanticsMaxExponent(HigherElementTypeSemantics)) ||
+ (HigherElementType == Ctx.LongDoubleTy &&
+ !Ctx.getTargetInfo().hasLongDoubleType())) {
+ // Retain the location of the first use of higher precision type.
+ if (!S.LocationOfExcessPrecisionNotSatisfied.isValid())
+ S.LocationOfExcessPrecisionNotSatisfied = OpLoc;
+ for (auto &[Type, Num] : S.ExcessPrecisionNotSatisfied) {
+ if (Type == HigherElementType) {
+ Num++;
+ return;
+ }
+ }
+ S.ExcessPrecisionNotSatisfied.push_back(std::make_pair(
+ HigherElementType, S.ExcessPrecisionNotSatisfied.size()));
+ }
+}
+
static void DiagnoseDivisionSizeofPointerOrArray(Sema &S, Expr *LHS, Expr *RHS,
SourceLocation Loc) {
const auto *LUE = dyn_cast<UnaryExprOrTypeTraitExpr>(LHS);
@@ -10685,6 +10724,7 @@ QualType Sema::CheckMultiplyDivideOperands(ExprResult
&LHS, ExprResult &RHS,
if (compType.isNull() || !compType->isArithmeticType())
return InvalidOperands(Loc, LHS, RHS);
if (IsDiv) {
+ DetectPrecisionLossInComplexDivision(*this, RHS.get()->getType(), Loc);
DiagnoseBadDivideOrRemainderValues(*this, LHS, RHS, Loc, IsDiv);
DiagnoseDivisionSizeofPointerOrArray(*this, LHS.get(), RHS.get(), Loc);
}
@@ -15314,39 +15354,6 @@ static void DiagnoseBinOpPrecedence(Sema &Self,
BinaryOperatorKind Opc,
DiagnoseShiftCompare(Self, OpLoc, LHSExpr, RHSExpr);
}
-static void DetectPrecisionLossInComplexDivision(Sema &S, SourceLocation OpLoc,
- Expr *Operand) {
- if (auto *CT = Operand->getType()->getAs<ComplexType>()) {
- QualType ElementType = CT->getElementType();
- bool IsComplexRangePromoted = S.getLangOpts().getComplexRange() ==
- LangOptions::ComplexRangeKind::CX_Promoted;
- if (ElementType->isFloatingType() && IsComplexRangePromoted) {
- ASTContext &Ctx = S.getASTContext();
- QualType HigherElementType = Ctx.GetHigherPrecisionFPType(ElementType);
- const llvm::fltSemantics &ElementTypeSemantics =
- Ctx.getFloatTypeSemantics(ElementType);
- const llvm::fltSemantics &HigherElementTypeSemantics =
- Ctx.getFloatTypeSemantics(HigherElementType);
- if ((llvm::APFloat::semanticsMaxExponent(ElementTypeSemantics) * 2 + 1 >
- llvm::APFloat::semanticsMaxExponent(HigherElementTypeSemantics)) ||
- (HigherElementType == Ctx.LongDoubleTy &&
- !Ctx.getTargetInfo().hasLongDoubleType())) {
- // Retain the location of the first use of higher precision type.
- if (!S.LocationOfExcessPrecisionNotSatisfied.isValid())
- S.LocationOfExcessPrecisionNotSatisfied = OpLoc;
- for (auto &[Type, Num] : S.ExcessPrecisionNotSatisfied) {
- if (Type == HigherElementType) {
- Num++;
- return;
- }
- }
- S.ExcessPrecisionNotSatisfied.push_back(std::make_pair(
- HigherElementType, S.ExcessPrecisionNotSatisfied.size()));
- }
- }
- }
-}
-
ExprResult Sema::ActOnBinOp(Scope *S, SourceLocation TokLoc,
tok::TokenKind Kind,
Expr *LHSExpr, Expr *RHSExpr) {
@@ -15357,11 +15364,6 @@ ExprResult Sema::ActOnBinOp(Scope *S, SourceLocation
TokLoc,
// Emit warnings for tricky precedence issues, e.g. "bitfield & 0x4 == 0"
DiagnoseBinOpPrecedence(*this, Opc, TokLoc, LHSExpr, RHSExpr);
- // Emit warnings if the requested higher precision type equal to the current
- // type precision.
- if (Kind == tok::TokenKind::slash)
- DetectPrecisionLossInComplexDivision(*this, TokLoc, LHSExpr);
-
BuiltinCountedByRefKind K =
BinaryOperator::isAssignmentOp(Opc) ? AssignmentKind : BinaryExprKind;
diff --git a/clang/test/Sema/complex-div-warn-higher-precision.c
b/clang/test/Sema/complex-div-warn-higher-precision.c
new file mode 100644
index 0000000000000..73a6e37b82e2c
--- /dev/null
+++ b/clang/test/Sema/complex-div-warn-higher-precision.c
@@ -0,0 +1,58 @@
+// RUN: %clang_cc1 %s -complex-range=promoted -triple x86_64-unknown-linux
-verify=no-diag \
+// RUN: -DDIV_CC -DDIV_RC -DDIVASSIGN -DDIVMIXEDFD -DDIVMIXEDID
+
+// RUN: %clang_cc1 %s -complex-range=promoted -triple x86_64-unknown-windows
-verify=no-diag
+// RUN: %clang_cc1 %s -complex-range=promoted -triple x86_64-unknown-windows
-verify -DDIV_CC
+// RUN: %clang_cc1 %s -complex-range=promoted -triple x86_64-unknown-windows
-verify -DDIV_RC
+// RUN: %clang_cc1 %s -complex-range=promoted -triple x86_64-unknown-windows
-verify -DDIVASSIGN
+// RUN: %clang_cc1 %s -complex-range=promoted -triple x86_64-unknown-windows
-verify -DDIVMIXEDFD
+// RUN: %clang_cc1 %s -complex-range=promoted -triple x86_64-unknown-windows
-verify -DDIVMIXEDID
+
+_Complex double div_ccf(_Complex float a, _Complex float b) {
+ return a / b;
+}
+
+_Complex double div_cr(_Complex double a, double b) {
+ return a / b;
+}
+
+_Complex double div_rr(double a, double b) {
+ return a / b;
+}
+
+_Complex int div_ii(_Complex int a, _Complex int b) {
+ return a / b;
+}
+
+#ifdef DIV_CC
+_Complex double div_cc(_Complex double a, const _Complex double b) {
+ return a / b; // #1
+}
+#endif // DIV_CC
+
+#ifdef DIV_RC
+_Complex double div_rc(double a, _Complex float b) {
+ return a / b; // #1
+}
+#endif // DIV_RC
+
+#ifdef DIVASSIGN
+_Complex double divassign(_Complex double a, _Complex double b) {
+ return a /= b; // #1
+}
+#endif // DIVASSIGN
+
+#ifdef DIVMIXEDFD
+_Complex double divmixedfd(_Complex float a, _Complex double b) {
+ return a / b; // #1
+}
+#endif // DIVMIXEDFD
+
+#ifdef DIVMIXEDID
+_Complex double divmixedid(_Complex int a, _Complex double b) {
+ return a / b; // #1
+}
+#endif // DIVMIXEDID
+
+// no-diag-no-diagnostics
+// expected-warning@#1 {{excess precision is requested but the target does not
support excess precision which may result in observable differences in complex
division behavior}}
From c62bde990396854bd4015c4ad19894e9297ebe18 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?M=C3=A9sz=C3=A1ros=20Gergely?= <maetv...@gmail.com>
Date: Fri, 21 Mar 2025 07:23:48 +0100
Subject: [PATCH 2/2] Reword comment to make it clearer
---
clang/lib/Sema/SemaExpr.cpp | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp
index 5001df20afe03..36068d1a4b94e 100644
--- a/clang/lib/Sema/SemaExpr.cpp
+++ b/clang/lib/Sema/SemaExpr.cpp
@@ -10593,7 +10593,7 @@ static void checkArithmeticNull(Sema &S, ExprResult
&LHS, ExprResult &RHS,
static void DetectPrecisionLossInComplexDivision(Sema &S, QualType DivisorTy,
SourceLocation OpLoc) {
- // Either real/real or complex/real division.
+ // If the divisor is real, then this is real/real or complex/real division.
// Either way there can be no precision loss.
auto *CT = DivisorTy->getAs<ComplexType>();
if (!CT)
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