https://github.com/mjklemm created https://github.com/llvm/llvm-project/pull/167118
It turns out that having `-ffast-math` as the only option to control optimizations for MOD for REAL kinds (PR #160660) is too coarse-grained for some applications. Thus, this PR adds back `-ffast-real-mod` to have more control over the optimization. The `-ffast-math` flag will still enable the optimization, and `-fno-fast-real-mod` allows one to disable it. >From 8ed0841fac6537afeacddb29d9c3a2c8eec9dca6 Mon Sep 17 00:00:00 2001 From: Michael Klemm <[email protected]> Date: Sat, 8 Nov 2025 11:03:17 +0100 Subject: [PATCH] [Flang] Add -ffast-real-mod back for further control of MOD optimizations --- clang/include/clang/Driver/Options.td | 3 + clang/lib/Driver/ToolChains/Flang.cpp | 2 + flang/include/flang/Support/LangOptions.def | 2 +- flang/lib/Frontend/CompilerInvocation.cpp | 5 +- flang/lib/Frontend/FrontendActions.cpp | 4 +- flang/lib/Optimizer/Builder/IntrinsicCall.cpp | 10 +- flang/test/Driver/fast-real-mod.f90 | 2 + flang/test/Lower/Intrinsics/fast-real-mod.f90 | 94 +++++++++---------- 8 files changed, 65 insertions(+), 57 deletions(-) diff --git a/clang/include/clang/Driver/Options.td b/clang/include/clang/Driver/Options.td index 11e81e032d5fc..fcefc236b9d82 100644 --- a/clang/include/clang/Driver/Options.td +++ b/clang/include/clang/Driver/Options.td @@ -2778,6 +2778,9 @@ def fno_unsafe_math_optimizations : Flag<["-"], "fno-unsafe-math-optimizations"> Group<f_Group>; def fassociative_math : Flag<["-"], "fassociative-math">, Visibility<[ClangOption, FlangOption]>, Group<f_Group>; def fno_associative_math : Flag<["-"], "fno-associative-math">, Visibility<[ClangOption, FlangOption]>, Group<f_Group>; +def ffast_real_mod : Flag<["-"], "ffast-real-mod">, + Group<f_Group>, Visibility<[FlangOption, FC1Option]>, + HelpText<"Enable optimization of MOD for REAL types">; def fno_fast_real_mod : Flag<["-"], "fno-fast-real-mod">, Group<f_Group>, Visibility<[FlangOption, FC1Option]>, HelpText<"Disable optimization of MOD for REAL types in presence of -ffast-math">; diff --git a/clang/lib/Driver/ToolChains/Flang.cpp b/clang/lib/Driver/ToolChains/Flang.cpp index 88bce181d40d2..c5230e5502cda 100644 --- a/clang/lib/Driver/ToolChains/Flang.cpp +++ b/clang/lib/Driver/ToolChains/Flang.cpp @@ -822,6 +822,8 @@ static void addFloatingPointOptions(const Driver &D, const ArgList &Args, complexRangeKindToStr(Range))); } + if (Args.hasArg(options::OPT_ffast_real_mod)) + CmdArgs.push_back("-ffast-real-mod"); if (Args.hasArg(options::OPT_fno_fast_real_mod)) CmdArgs.push_back("-fno-fast-real-mod"); diff --git a/flang/include/flang/Support/LangOptions.def b/flang/include/flang/Support/LangOptions.def index e7185c836f45b..e310ecf37a52d 100644 --- a/flang/include/flang/Support/LangOptions.def +++ b/flang/include/flang/Support/LangOptions.def @@ -61,7 +61,7 @@ LANGOPT(OpenMPNoNestedParallelism, 1, 0) /// Use SIMD only OpenMP support. LANGOPT(OpenMPSimd, 1, false) /// Enable fast MOD operations for REAL -LANGOPT(NoFastRealMod, 1, false) +LANGOPT(FastRealMod, 1, false) LANGOPT(VScaleMin, 32, 0) ///< Minimum vscale range value LANGOPT(VScaleMax, 32, 0) ///< Maximum vscale range value diff --git a/flang/lib/Frontend/CompilerInvocation.cpp b/flang/lib/Frontend/CompilerInvocation.cpp index f05c4cfccf7fc..bea3dfc6638a8 100644 --- a/flang/lib/Frontend/CompilerInvocation.cpp +++ b/flang/lib/Frontend/CompilerInvocation.cpp @@ -1428,11 +1428,14 @@ static bool parseFloatingPointArgs(CompilerInvocation &invoc, opts.ReciprocalMath = true; opts.ApproxFunc = true; opts.NoSignedZeros = true; + opts.FastRealMod = true; opts.setFPContractMode(Fortran::common::LangOptions::FPM_Fast); } + if (args.hasArg(clang::driver::options::OPT_ffast_real_mod)) + opts.FastRealMod = true; if (args.hasArg(clang::driver::options::OPT_fno_fast_real_mod)) - opts.NoFastRealMod = true; + opts.FastRealMod = false; return true; } diff --git a/flang/lib/Frontend/FrontendActions.cpp b/flang/lib/Frontend/FrontendActions.cpp index 159d08a2797b3..ddf125f9bb216 100644 --- a/flang/lib/Frontend/FrontendActions.cpp +++ b/flang/lib/Frontend/FrontendActions.cpp @@ -277,11 +277,11 @@ bool CodeGenAction::beginSourceFileAction() { ci.getInvocation().getLangOpts().OpenMPVersion); } - if (ci.getInvocation().getLangOpts().NoFastRealMod) { + if (ci.getInvocation().getLangOpts().FastRealMod) { mlir::ModuleOp mod = lb.getModule(); mod.getOperation()->setAttr( mlir::StringAttr::get(mod.getContext(), - llvm::Twine{"fir.no_fast_real_mod"}), + llvm::Twine{"fir.fast_real_mod"}), mlir::BoolAttr::get(mod.getContext(), true)); } diff --git a/flang/lib/Optimizer/Builder/IntrinsicCall.cpp b/flang/lib/Optimizer/Builder/IntrinsicCall.cpp index 3eb60448fae38..9c8dbd6a65b4d 100644 --- a/flang/lib/Optimizer/Builder/IntrinsicCall.cpp +++ b/flang/lib/Optimizer/Builder/IntrinsicCall.cpp @@ -6509,11 +6509,9 @@ static mlir::Value genFastMod(fir::FirOpBuilder &builder, mlir::Location loc, mlir::Value IntrinsicLibrary::genMod(mlir::Type resultType, llvm::ArrayRef<mlir::Value> args) { auto mod = builder.getModule(); - bool dontUseFastRealMod = false; - bool canUseApprox = mlir::arith::bitEnumContainsAny( - builder.getFastMathFlags(), mlir::arith::FastMathFlags::afn); - if (auto attr = mod->getAttrOfType<mlir::BoolAttr>("fir.no_fast_real_mod")) - dontUseFastRealMod = attr.getValue(); + bool useFastRealMod = false; + if (auto attr = mod->getAttrOfType<mlir::BoolAttr>("fir.fast_real_mod")) + useFastRealMod = attr.getValue(); assert(args.size() == 2); if (resultType.isUnsignedInteger()) { @@ -6526,7 +6524,7 @@ mlir::Value IntrinsicLibrary::genMod(mlir::Type resultType, if (mlir::isa<mlir::IntegerType>(resultType)) return mlir::arith::RemSIOp::create(builder, loc, args[0], args[1]); - if (resultType.isFloat() && canUseApprox && !dontUseFastRealMod) { + if (resultType.isFloat() && useFastRealMod) { // Treat MOD as an approximate function and code-gen inline code // instead of calling into the Fortran runtime library. return builder.createConvert(loc, resultType, diff --git a/flang/test/Driver/fast-real-mod.f90 b/flang/test/Driver/fast-real-mod.f90 index 4ea9b26e64753..8184f334c3d85 100644 --- a/flang/test/Driver/fast-real-mod.f90 +++ b/flang/test/Driver/fast-real-mod.f90 @@ -1,5 +1,7 @@ +! RUN: %flang -ffast-real-mod -### -c %s 2>&1 | FileCheck %s -check-prefix CHECK-FAST-REAL-MOD ! RUN: %flang -fno-fast-real-mod -### -c %s 2>&1 | FileCheck %s -check-prefix CHECK-NO-FAST-REAL-MOD +! CHECK-FAST-REAL-MOD: "-ffast-real-mod" ! CHECK-NO-FAST-REAL-MOD: "-fno-fast-real-mod" program test diff --git a/flang/test/Lower/Intrinsics/fast-real-mod.f90 b/flang/test/Lower/Intrinsics/fast-real-mod.f90 index f80f7203ad1a2..8613c0eb3c2f6 100644 --- a/flang/test/Lower/Intrinsics/fast-real-mod.f90 +++ b/flang/test/Lower/Intrinsics/fast-real-mod.f90 @@ -1,24 +1,24 @@ -! RUN: %flang_fc1 -ffast-math -emit-mlir -o - %s | FileCheck %s --check-prefixes=CHECK%if target=x86_64{{.*}} %{,CHECK-KIND10%}%if flang-supports-f128-math %{,CHECK-KIND16%} +! RUN: %flang_fc1 -ffast-real-mod -emit-mlir -o - %s | FileCheck %s --check-prefixes=CHECK-FRM%if target=x86_64{{.*}} %{,CHECK-FRM-KIND10%}%if flang-supports-f128-math %{,CHECK-FRM-KIND16%} +! RUN: %flang_fc1 -ffast-math -emit-mlir -o - %s | FileCheck %s --check-prefixes=CHECK-FRM%if target=x86_64{{.*}} %{,CHECK-FRM-KIND10%}%if flang-supports-f128-math %{,CHECK-FRM-KIND16%} ! RUN: %flang_fc1 -ffast-math -fno-fast-real-mod -emit-mlir -o - %s | FileCheck %s --check-prefixes=CHECK-NFRM%if target=x86_64{{.*}} %{,CHECK-NFRM-KIND10%}%if flang-supports-f128-math %{,CHECK-NFRM-KIND16%} -! TODO: check line that fir.fast_real_mod is not there -! CHECK-NFRM: module attributes {{{.*}}fir.no_fast_real_mod = true{{.*}}} +! CHECK,CHECK-FRM: module attributes {{{.*}}fir.fast_real_mod = true{{.*}}} ! CHECK-LABEL: @_QPmod_real4 subroutine mod_real4(r, a, p) implicit none real(kind=4) :: r, a, p -! CHECK: %[[A:.*]] = fir.declare{{.*}}a" -! CHECK: %[[P:.*]] = fir.declare{{.*}}p" -! CHECK: %[[R:.*]] = fir.declare{{.*}}r" -! CHECK: %[[A_LOAD:.*]] = fir.load %[[A]] -! CHECK: %[[P_LOAD:.*]] = fir.load %[[P]] -! CHECK: %[[DIV:.*]] = arith.divf %[[A_LOAD]], %[[P_LOAD]] fastmath<fast> : f32 -! CHECK: %[[CV1:.*]] = fir.convert %[[DIV]] : (f32) -> si32 -! CHECK: %[[CV2:.*]] = fir.convert %[[CV1]] : (si32) -> f32 -! CHECK: %[[MUL:.*]] = arith.mulf %[[CV2]], %[[P_LOAD]] fastmath<fast> : f32 -! CHECK: %[[SUB:.*]] = arith.subf %[[A_LOAD]], %[[MUL]] fastmath<fast> : f32 -! CHECK: fir.store %[[SUB]] to %[[R]] : !fir.ref<f32> +! CHECK-FRM: %[[A:.*]] = fir.declare{{.*}}a" +! CHECK-FRM: %[[P:.*]] = fir.declare{{.*}}p" +! CHECK-FRM: %[[R:.*]] = fir.declare{{.*}}r" +! CHECK-FRM: %[[A_LOAD:.*]] = fir.load %[[A]] +! CHECK-FRM: %[[P_LOAD:.*]] = fir.load %[[P]] +! CHECK-FRM: %[[DIV:.*]] = arith.divf %[[A_LOAD]], %[[P_LOAD]] fastmath<{{.*}}> : f32 +! CHECK-FRM: %[[CV1:.*]] = fir.convert %[[DIV]] : (f32) -> si32 +! CHECK-FRM: %[[CV2:.*]] = fir.convert %[[CV1]] : (si32) -> f32 +! CHECK-FRM: %[[MUL:.*]] = arith.mulf %[[CV2]], %[[P_LOAD]] fastmath<{{.*}}> : f32 +! CHECK-FRM: %[[SUB:.*]] = arith.subf %[[A_LOAD]], %[[MUL]] fastmath<{{.*}}> : f32 +! CHECK-FRM: fir.store %[[SUB]] to %[[R]] : !fir.ref<f32> ! CHECK-NFRM: fir.call @_FortranAModReal4(%{{.*}}, %{{.*}}, %{{.*}}, %{{.*}}) {{.*}}: (f32, f32, !fir.ref<i8>, i32) -> f32 r = mod(a, p) end subroutine mod_real4 @@ -27,17 +27,17 @@ end subroutine mod_real4 subroutine mod_real8(r, a, p) implicit none real(kind=8) :: r, a, p -! CHECK: %[[A:.*]] = fir.declare{{.*}}a" -! CHECK: %[[P:.*]] = fir.declare{{.*}}p" -! CHECK: %[[R:.*]] = fir.declare{{.*}}r" -! CHECK: %[[A_LOAD:.*]] = fir.load %[[A]] -! CHECK: %[[P_LOAD:.*]] = fir.load %[[P]] -! CHECK: %[[DIV:.*]] = arith.divf %[[A_LOAD]], %[[P_LOAD]] fastmath<fast> : f64 -! CHECK: %[[CV1:.*]] = fir.convert %[[DIV]] : (f64) -> si64 -! CHECK: %[[CV2:.*]] = fir.convert %[[CV1]] : (si64) -> f64 -! CHECK: %[[MUL:.*]] = arith.mulf %[[CV2]], %[[P_LOAD]] fastmath<fast> : f64 -! CHECK: %[[SUB:.*]] = arith.subf %[[A_LOAD]], %[[MUL]] fastmath<fast> : f64 -! CHECK: fir.store %[[SUB]] to %[[R]] : !fir.ref<f64> +! CHECK-FRM: %[[A:.*]] = fir.declare{{.*}}a" +! CHECK-FRM: %[[P:.*]] = fir.declare{{.*}}p" +! CHECK-FRM: %[[R:.*]] = fir.declare{{.*}}r" +! CHECK-FRM: %[[A_LOAD:.*]] = fir.load %[[A]] +! CHECK-FRM: %[[P_LOAD:.*]] = fir.load %[[P]] +! CHECK-FRM: %[[DIV:.*]] = arith.divf %[[A_LOAD]], %[[P_LOAD]] fastmath<{{.*}}> : f64 +! CHECK-FRM: %[[CV1:.*]] = fir.convert %[[DIV]] : (f64) -> si64 +! CHECK-FRM: %[[CV2:.*]] = fir.convert %[[CV1]] : (si64) -> f64 +! CHECK-FRM: %[[MUL:.*]] = arith.mulf %[[CV2]], %[[P_LOAD]] fastmath<{{.*}}> : f64 +! CHECK-FRM: %[[SUB:.*]] = arith.subf %[[A_LOAD]], %[[MUL]] fastmath<{{.*}}> : f64 +! CHECK-FRM: fir.store %[[SUB]] to %[[R]] : !fir.ref<f64> ! CHECK-NFRM: fir.call @_FortranAModReal8(%{{.*}}, %{{.*}}, %{{.*}}, %{{.*}}) {{.*}}: (f64, f64, !fir.ref<i8>, i32) -> f64 r = mod(a, p) end subroutine mod_real8 @@ -47,17 +47,17 @@ subroutine mod_real10(r, a, p) implicit none integer, parameter :: kind10 = merge(10, 4, selected_real_kind(p=18).eq.10) real(kind=kind10) :: r, a, p -! CHECK-KIND10: %[[A:.*]] = fir.declare{{.*}}a" -! CHECK-KIND10: %[[P:.*]] = fir.declare{{.*}}p" -! CHECK-KIND10: %[[R:.*]] = fir.declare{{.*}}r" -! CHECK-KIND10: %[[A_LOAD:.*]] = fir.load %[[A]] -! CHECK-KIND10: %[[P_LOAD:.*]] = fir.load %[[P]] -! CHECK-KIND10: %[[DIV:.*]] = arith.divf %[[A_LOAD]], %[[P_LOAD]] fastmath<fast> : f80 -! CHECK-KIND10: %[[CV1:.*]] = fir.convert %[[DIV]] : (f80) -> si80 -! CHECK-KIND10: %[[CV2:.*]] = fir.convert %[[CV1]] : (si80) -> f80 -! CHECK-KIND10: %[[MUL:.*]] = arith.mulf %[[CV2]], %[[P_LOAD]] fastmath<fast> : f80 -! CHECK-KIND10: %[[SUB:.*]] = arith.subf %[[A_LOAD]], %[[MUL]] fastmath<fast> : f80 -! CHECK-KIND10: fir.store %[[SUB]] to %[[R]] : !fir.ref<f80> +! CHECK-FRM-KIND10: %[[A:.*]] = fir.declare{{.*}}a" +! CHECK-FRM-KIND10: %[[P:.*]] = fir.declare{{.*}}p" +! CHECK-FRM-KIND10: %[[R:.*]] = fir.declare{{.*}}r" +! CHECK-FRM-KIND10: %[[A_LOAD:.*]] = fir.load %[[A]] +! CHECK-FRM-KIND10: %[[P_LOAD:.*]] = fir.load %[[P]] +! CHECK-FRM-KIND10: %[[DIV:.*]] = arith.divf %[[A_LOAD]], %[[P_LOAD]] fastmath<{{.*}}> : f80 +! CHECK-FRM-KIND10: %[[CV1:.*]] = fir.convert %[[DIV]] : (f80) -> si80 +! CHECK-FRM-KIND10: %[[CV2:.*]] = fir.convert %[[CV1]] : (si80) -> f80 +! CHECK-FRM-KIND10: %[[MUL:.*]] = arith.mulf %[[CV2]], %[[P_LOAD]] fastmath<{{.*}}> : f80 +! CHECK-FRM-KIND10: %[[SUB:.*]] = arith.subf %[[A_LOAD]], %[[MUL]] fastmath<{{.*}}> : f80 +! CHECK-FRM-KIND10: fir.store %[[SUB]] to %[[R]] : !fir.ref<f80> ! CHECK-NFRM-KIND10: fir.call @_FortranAModReal10(%{{.*}}, %{{.*}}, %{{.*}}, %{{.*}}) {{.*}}: (f80, f80, !fir.ref<i8>, i32) -> f80 r = mod(a, p) end subroutine mod_real10 @@ -67,17 +67,17 @@ subroutine mod_real16(r, a, p) implicit none integer, parameter :: kind16 = merge(16, 4, selected_real_kind(p=33).eq.16) real(kind=kind16) :: r, a, p -! CHECK-KIND16: %[[A:.*]] = fir.declare{{.*}}a" -! CHECK-KIND16: %[[P:.*]] = fir.declare{{.*}}p" -! CHECK-KIND16: %[[R:.*]] = fir.declare{{.*}}r" -! CHECK-KIND16: %[[A_LOAD:.*]] = fir.load %[[A]] -! CHECK-KIND16: %[[P_LOAD:.*]] = fir.load %[[P]] -! CHECK-KIND16: %[[DIV:.*]] = arith.divf %[[A_LOAD]], %[[P_LOAD]] fastmath<fast> : f128 -! CHECK-KIND16: %[[CV1:.*]] = fir.convert %[[DIV]] : (f128) -> si128 -! CHECK-KIND16: %[[CV2:.*]] = fir.convert %[[CV1]] : (si128) -> f128 -! CHECK-KIND16: %[[MUL:.*]] = arith.mulf %[[CV2]], %[[P_LOAD]] fastmath<fast> : f128 -! CHECK-KIND16: %[[SUB:.*]] = arith.subf %[[A_LOAD]], %[[MUL]] fastmath<fast> : f128 -! CHECK-KIND16: fir.store %[[SUB]] to %[[R]] : !fir.ref<f128> +! CHECK-FRM-KIND16: %[[A:.*]] = fir.declare{{.*}}a" +! CHECK-FRM-KIND16: %[[P:.*]] = fir.declare{{.*}}p" +! CHECK-FRM-KIND16: %[[R:.*]] = fir.declare{{.*}}r" +! CHECK-FRM-KIND16: %[[A_LOAD:.*]] = fir.load %[[A]] +! CHECK-FRM-KIND16: %[[P_LOAD:.*]] = fir.load %[[P]] +! CHECK-FRM-KIND16: %[[DIV:.*]] = arith.divf %[[A_LOAD]], %[[P_LOAD]] fastmath<{{.*}}> : f128 +! CHECK-FRM-KIND16: %[[CV1:.*]] = fir.convert %[[DIV]] : (f128) -> si128 +! CHECK-FRM-KIND16: %[[CV2:.*]] = fir.convert %[[CV1]] : (si128) -> f128 +! CHECK-FRM-KIND16: %[[MUL:.*]] = arith.mulf %[[CV2]], %[[P_LOAD]] fastmath<{{.*}}> : f128 +! CHECK-FRM-KIND16: %[[SUB:.*]] = arith.subf %[[A_LOAD]], %[[MUL]] fastmath<{{.*}}> : f128 +! CHECK-FRM-KIND16: fir.store %[[SUB]] to %[[R]] : !fir.ref<f128> ! CHECK-NFRM-KIND16: fir.call @_FortranAModReal16(%{{.*}}, %{{.*}}, %{{.*}}, %{{.*}}) {{.*}}: (f128, f128, !fir.ref<i8>, i32) -> f128 r = mod(a, p) end subroutine mod_real16 _______________________________________________ cfe-commits mailing list [email protected] https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
