llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT--> @llvm/pr-subscribers-clang Author: Andy Kaylor (andykaylor) <details> <summary>Changes</summary> This is an attempt to better align the denormal handling of -ffp-model=fast with the behavior of -ffast-math. The clang user's manual claims that -ffp-model=fast "behaves identically to specifying both -ffast-math and -ffp-contract=fast." That isn't entirely correct. One difference is that -ffast-math causes crtfastmath.o to be linked if it is available, and passes -fdenormal-fp-math=PreserveSign as a -cc1 option when crtfastmath.o is available. I'm not sure the current behavior is reasonable and consistent for all tool chains, but I'm not trying to fix that here. This is just trying to make an incremental improvement. I am going to be proposing further changes to -ffp-model=fast, decoupling it from -ffast-math and introducing a new -ffp-model=aggressive that matches the current behavior, but I wanted to solidfy the current behavior before I do that. --- Full diff: https://github.com/llvm/llvm-project/pull/89477.diff 6 Files Affected: - (modified) clang/docs/UsersManual.rst (+2-2) - (modified) clang/lib/Driver/ToolChain.cpp (+7-1) - (modified) clang/lib/Driver/ToolChains/Clang.cpp (+4) - (modified) clang/test/Driver/default-denormal-fp-math.c (+3) - (modified) clang/test/Driver/linux-ld.c (+3) - (modified) clang/test/Driver/solaris-ld.c (+3) ``````````diff diff --git a/clang/docs/UsersManual.rst b/clang/docs/UsersManual.rst index c464bc3a69adc5..00bb1e779308ef 100644 --- a/clang/docs/UsersManual.rst +++ b/clang/docs/UsersManual.rst @@ -1452,8 +1452,8 @@ floating point semantic models: precise (the default), strict, and fast. "fenv_access", "off", "on", "off" "rounding_mode", "tonearest", "dynamic", "tonearest" "contract", "on", "off", "fast" - "denormal_fp_math", "IEEE", "IEEE", "IEEE" - "denormal_fp32_math", "IEEE","IEEE", "IEEE" + "denormal_fp_math", "IEEE", "IEEE", "target-dependent" + "denormal_fp32_math", "IEEE","IEEE", "target-dependent" "support_math_errno", "on", "on", "off" "no_honor_nans", "off", "off", "on" "no_honor_infinities", "off", "off", "on" diff --git a/clang/lib/Driver/ToolChain.cpp b/clang/lib/Driver/ToolChain.cpp index 237092ed07e5dc..a36d8eb1750a2d 100644 --- a/clang/lib/Driver/ToolChain.cpp +++ b/clang/lib/Driver/ToolChain.cpp @@ -1314,11 +1314,17 @@ bool ToolChain::isFastMathRuntimeAvailable(const ArgList &Args, Arg *A = Args.getLastArg(options::OPT_ffast_math, options::OPT_fno_fast_math, options::OPT_funsafe_math_optimizations, - options::OPT_fno_unsafe_math_optimizations); + options::OPT_fno_unsafe_math_optimizations, + options::OPT_ffp_model_EQ); if (!A || A->getOption().getID() == options::OPT_fno_fast_math || A->getOption().getID() == options::OPT_fno_unsafe_math_optimizations) return false; + if (A && A->getOption().getID() == options::OPT_ffp_model_EQ) { + StringRef Model = A->getValue(); + if (!Model.equals("fast")) + return false; + } } // If crtfastmath.o exists add it to the arguments. Path = GetFilePath("crtfastmath.o"); diff --git a/clang/lib/Driver/ToolChains/Clang.cpp b/clang/lib/Driver/ToolChains/Clang.cpp index 456ea74caadb00..0ee74855891b03 100644 --- a/clang/lib/Driver/ToolChains/Clang.cpp +++ b/clang/lib/Driver/ToolChains/Clang.cpp @@ -2942,6 +2942,10 @@ static void RenderFloatingPointOptions(const ToolChain &TC, const Driver &D, if (Val.equals("fast")) { FPModel = Val; applyFastMath(); + // The target-specific getDefaultDenormalModeForType handler should + // account for -ffp-model=fast and choose its behavior + DenormalFPMath = DefaultDenormalFPMath; + DenormalFP32Math = DefaultDenormalFP32Math; } else if (Val.equals("precise")) { optID = options::OPT_ffp_contract; FPModel = Val; diff --git a/clang/test/Driver/default-denormal-fp-math.c b/clang/test/Driver/default-denormal-fp-math.c index 5f87e151df49e4..61787a8bbe82b8 100644 --- a/clang/test/Driver/default-denormal-fp-math.c +++ b/clang/test/Driver/default-denormal-fp-math.c @@ -5,12 +5,15 @@ // crtfastmath enables ftz and daz // RUN: %clang -### -target x86_64-unknown-linux-gnu -ffast-math --sysroot=%S/Inputs/basic_linux_tree -c %s -v 2>&1 | FileCheck -check-prefix=CHECK-PRESERVESIGN %s +// RUN: %clang -### -target x86_64-unknown-linux-gnu -ffp-model=fast --sysroot=%S/Inputs/basic_linux_tree -c %s -v 2>&1 | FileCheck -check-prefix=CHECK-PRESERVESIGN %s // crt not linked in with nostartfiles // RUN: %clang -### -target x86_64-unknown-linux-gnu -ffast-math -nostartfiles --sysroot=%S/Inputs/basic_linux_tree -c %s -v 2>&1 | FileCheck -check-prefix=CHECK-IEEE %s +// RUN: %clang -### -target x86_64-unknown-linux-gnu -ffp-model=fast -nostartfiles --sysroot=%S/Inputs/basic_linux_tree -c %s -v 2>&1 | FileCheck -check-prefix=CHECK-IEEE %s // If there's no crtfastmath, don't assume ftz/daz // RUN: %clang -### -target x86_64-unknown-linux-gnu -ffast-math --sysroot=/dev/null -c %s -v 2>&1 | FileCheck -check-prefix=CHECK-IEEE %s +// RUN: %clang -### -target x86_64-unknown-linux-gnu -ffp-model=fast --sysroot=/dev/null -c %s -v 2>&1 | FileCheck -check-prefix=CHECK-IEEE %s // RUN: %clang -### -target x86_64-scei-ps4 -c %s -v 2>&1 | FileCheck -check-prefix=CHECK-PRESERVESIGN %s diff --git a/clang/test/Driver/linux-ld.c b/clang/test/Driver/linux-ld.c index d918f4f2d7dbd9..a3ad564082b966 100644 --- a/clang/test/Driver/linux-ld.c +++ b/clang/test/Driver/linux-ld.c @@ -1417,6 +1417,9 @@ // RUN: %clang --target=x86_64-unknown-linux -no-pie -### %s -funsafe-math-optimizations\ // RUN: --sysroot=%S/Inputs/basic_linux_tree 2>&1 \ // RUN: | FileCheck --check-prefix=CHECK-CRTFASTMATH %s +// RUN: %clang --target=x86_64-unknown-linux -no-pie -### %s -ffp-model=fast \ +// RUN: --sysroot=%S/Inputs/basic_linux_tree 2>&1 \ +// RUN: | FileCheck --check-prefix=CHECK-CRTFASTMATH %s // RUN: %clang --target=x86_64-unknown-linux -no-pie -### %s -Ofast\ // RUN: --sysroot=%S/Inputs/basic_linux_tree 2>&1 \ // RUN: | FileCheck --check-prefix=CHECK-CRTFASTMATH %s diff --git a/clang/test/Driver/solaris-ld.c b/clang/test/Driver/solaris-ld.c index 6d74389e89222c..ce0728d392bf23 100644 --- a/clang/test/Driver/solaris-ld.c +++ b/clang/test/Driver/solaris-ld.c @@ -193,6 +193,9 @@ // RUN: %clang --target=sparc-sun-solaris2.11 -### %s -ffast-math \ // RUN: --sysroot=%S/Inputs/solaris_sparc_tree 2>&1 \ // RUN: | FileCheck --check-prefix=CHECK-CRTFASTMATH-SPARC32 %s +// RUN: %clang --target=sparc-sun-solaris2.11 -### %s -ffp-model=fast \ +// RUN: --sysroot=%S/Inputs/solaris_sparc_tree 2>&1 \ +// RUN: | FileCheck --check-prefix=CHECK-CRTFASTMATH-SPARC32 %s // CHECK-CRTFASTMATH-SPARC32: "-isysroot" "[[SYSROOT:[^"]+]]" // CHECK-CRTFASTMATH-SPARC32: "[[SYSROOT]]/usr/gcc/4.8/lib/gcc/sparc-sun-solaris2.11/4.8.2{{/|\\\\}}crtfastmath.o" // CHECK-NOCRTFASTMATH-SPARC32-NOT: crtfastmath.o `````````` </details> https://github.com/llvm/llvm-project/pull/89477 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
