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Fix math-errno issue (#66381)

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Update handling of math errno. This change updates the logic for
generation of math intrinics in place of math library function calls.
The previous logic https://reviews.llvm.org/D151834 was incorrectly
using intrinsics when math errno handling was needed at optimization
levels above -O0.
This also fixes issue mentioned in https://reviews.llvm.org/D151834 by
@uabelho
This is joint work with @andykaylor Andy.
This commit is contained in:
Zahira Ammarguellat
2023-09-19 06:13:02 -07:00
committed by GitHub
parent 6d1c6ecbdc
commit a292e7edf8
3 changed files with 37 additions and 6 deletions
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39
clang/lib/CodeGen/CGBuiltin.cpp
View File

@@ -2312,8 +2312,8 @@ RValue CodeGenFunction::EmitBuiltinExpr(const GlobalDecl GD, unsigned BuiltinID,
const unsigned BuiltinIDIfNoAsmLabel =
FD->hasAttr<AsmLabelAttr>() ? 0 : BuiltinID;
bool ErrnoOverriden = false;
// True if math-errno is overriden via the
std::optional<bool> ErrnoOverriden;
// ErrnoOverriden is true if math-errno is overriden via the
// '#pragma float_control(precise, on)'. This pragma disables fast-math,
// which implies math-errno.
if (E->hasStoredFPFeatures()) {
@@ -2329,8 +2329,8 @@ RValue CodeGenFunction::EmitBuiltinExpr(const GlobalDecl GD, unsigned BuiltinID,
// using the '#pragma float_control(precise, off)', and
// attribute opt-none hasn't been seen.
bool ErrnoOverridenToFalseWithOpt =
!ErrnoOverriden && !OptNone &&
CGM.getCodeGenOpts().OptimizationLevel != 0;
ErrnoOverriden.has_value() && !ErrnoOverriden.value() && !OptNone &&
CGM.getCodeGenOpts().OptimizationLevel != 0;
// There are LLVM math intrinsics/instructions corresponding to math library
// functions except the LLVM op will never set errno while the math library
@@ -2339,6 +2339,30 @@ RValue CodeGenFunction::EmitBuiltinExpr(const GlobalDecl GD, unsigned BuiltinID,
// LLVM counterparts if the call is marked 'const' (known to never set errno).
// In case FP exceptions are enabled, the experimental versions of the
// intrinsics model those.
bool ConstAlways =
getContext().BuiltinInfo.isConst(BuiltinID);
// There's a special case with the fma builtins where they are always const
// if the target environment is GNU or the target is OS is Windows and we're
// targeting the MSVCRT.dll environment.
// FIXME: This list can be become outdated. Need to find a way to get it some
// other way.
switch (BuiltinID) {
case Builtin::BI__builtin_fma:
case Builtin::BI__builtin_fmaf:
case Builtin::BI__builtin_fmal:
case Builtin::BIfma:
case Builtin::BIfmaf:
case Builtin::BIfmal: {
auto &Trip = CGM.getTriple();
if (Trip.isGNUEnvironment() || Trip.isOSMSVCRT())
ConstAlways = true;
break;
}
default:
break;
}
bool ConstWithoutErrnoAndExceptions =
getContext().BuiltinInfo.isConstWithoutErrnoAndExceptions(BuiltinID);
bool ConstWithoutExceptions =
@@ -2362,14 +2386,17 @@ RValue CodeGenFunction::EmitBuiltinExpr(const GlobalDecl GD, unsigned BuiltinID,
bool ConstWithoutErrnoOrExceptions =
ConstWithoutErrnoAndExceptions || ConstWithoutExceptions;
bool GenerateIntrinsics =
FD->hasAttr<ConstAttr>() && !ErrnoOverriden && !OptNone;
(ConstAlways && !OptNone) ||
(!getLangOpts().MathErrno &&
!(ErrnoOverriden.has_value() && ErrnoOverriden.value()) && !OptNone);
if (!GenerateIntrinsics) {
GenerateIntrinsics =
ConstWithoutErrnoOrExceptions && !ConstWithoutErrnoAndExceptions;
if (!GenerateIntrinsics)
GenerateIntrinsics =
ConstWithoutErrnoOrExceptions &&
(!getLangOpts().MathErrno && !ErrnoOverriden && !OptNone);
(!getLangOpts().MathErrno &&
!(ErrnoOverriden.has_value() && ErrnoOverriden.value()) && !OptNone);
if (!GenerateIntrinsics)
GenerateIntrinsics =
ConstWithoutErrnoOrExceptions && ErrnoOverridenToFalseWithOpt;

2
clang/test/CodeGen/math-builtins.c
View File

@@ -1,5 +1,7 @@
// RUN: %clang_cc1 -triple x86_64-unknown-unknown -w -S -o - -emit-llvm %s | FileCheck %s -check-prefix=NO__ERRNO
// RUN: %clang_cc1 -triple x86_64-unknown-unknown -w -S -o - -emit-llvm -fmath-errno %s | FileCheck %s -check-prefix=HAS_ERRNO
// RUN: %clang_cc1 -triple x86_64-unknown-unknown -w -S -o - -emit-llvm -disable-llvm-passes -O2 %s | FileCheck %s -check-prefix=NO__ERRNO
// RUN: %clang_cc1 -triple x86_64-unknown-unknown -w -S -o - -emit-llvm -disable-llvm-passes -O2 -fmath-errno %s | FileCheck %s -check-prefix=HAS_ERRNO
// RUN: %clang_cc1 -triple x86_64-unknown-unknown-gnu -w -S -o - -emit-llvm -fmath-errno %s | FileCheck %s --check-prefix=HAS_ERRNO_GNU
// RUN: %clang_cc1 -triple x86_64-unknown-windows-msvc -w -S -o - -emit-llvm -fmath-errno %s | FileCheck %s --check-prefix=HAS_ERRNO_WIN

2
clang/test/CodeGen/math-libcalls.c
View File

@@ -1,5 +1,7 @@
// RUN: %clang_cc1 -triple x86_64-unknown-unknown -Wno-implicit-function-declaration -w -S -o - -emit-llvm %s | FileCheck %s --check-prefix=NO__ERRNO
// RUN: %clang_cc1 -triple x86_64-unknown-unknown -Wno-implicit-function-declaration -w -S -o - -emit-llvm -fmath-errno %s | FileCheck %s --check-prefix=HAS_ERRNO
// RUN: %clang_cc1 -triple x86_64-unknown-unknown -Wno-implicit-function-declaration -w -S -o - -emit-llvm -disable-llvm-passes -O2 %s | FileCheck %s --check-prefix=NO__ERRNO
// RUN: %clang_cc1 -triple x86_64-unknown-unknown -Wno-implicit-function-declaration -w -S -o - -emit-llvm -disable-llvm-passes -O2 -fmath-errno %s | FileCheck %s --check-prefix=HAS_ERRNO
// RUN: %clang_cc1 -triple x86_64-unknown-unknown -Wno-implicit-function-declaration -w -S -o - -emit-llvm -ffp-exception-behavior=maytrap %s | FileCheck %s --check-prefix=HAS_MAYTRAP
// RUN: %clang_cc1 -triple x86_64-unknown-unknown-gnu -Wno-implicit-function-declaration -w -S -o - -emit-llvm -fmath-errno %s | FileCheck %s --check-prefix=HAS_ERRNO_GNU
// RUN: %clang_cc1 -triple x86_64-unknown-windows-msvc -Wno-implicit-function-declaration -w -S -o - -emit-llvm -fmath-errno %s | FileCheck %s --check-prefix=HAS_ERRNO_WIN