zahiraam updated this revision to Diff 386014.
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D107994/new/
https://reviews.llvm.org/D107994
Files:
clang/docs/ReleaseNotes.rst
clang/docs/UsersManual.rst
clang/lib/Driver/ToolChains/Clang.cpp
clang/test/CodeGen/ffp-contract-option.c
clang/test/CodeGen/ffp-model.c
clang/test/CodeGen/ppc-emmintrin.c
clang/test/CodeGen/ppc-xmmintrin.c
clang/test/Driver/fp-model.c
clang/test/Misc/ffp-contract.c
Index: clang/test/Misc/ffp-contract.c
===================================================================
--- /dev/null
+++ clang/test/Misc/ffp-contract.c
@@ -0,0 +1,10 @@
+// RUN: %clang_cc1 -O3 -ffp-contract=fast -triple=aarch64-apple-darwin \
+// RUN: -S -o - %s | FileCheck --check-prefix=CHECK-FMADD %s
+// REQUIRES: aarch64-registered-target
+
+float fma_test1(float a, float b, float c) {
+ // CHECK-FMADD: fmadd
+ float x = a * b;
+ float y = x + c;
+ return y;
+}
Index: clang/test/Driver/fp-model.c
===================================================================
--- clang/test/Driver/fp-model.c
+++ clang/test/Driver/fp-model.c
@@ -99,7 +99,7 @@
// RUN: %clang -### -nostdinc -ffp-model=precise -c %s 2>&1 \
// RUN: | FileCheck --check-prefix=CHECK-FPM-PRECISE %s
// CHECK-FPM-PRECISE: "-cc1"
-// CHECK-FPM-PRECISE: "-ffp-contract=fast"
+// CHECK-FPM-PRECISE: "-ffp-contract=on"
// CHECK-FPM-PRECISE: "-fno-rounding-math"
// RUN: %clang -### -nostdinc -ffp-model=strict -c %s 2>&1 \
Index: clang/test/CodeGen/ppc-xmmintrin.c
===================================================================
--- clang/test/CodeGen/ppc-xmmintrin.c
+++ clang/test/CodeGen/ppc-xmmintrin.c
@@ -2,11 +2,11 @@
// REQUIRES: powerpc-registered-target
// RUN: %clang -S -emit-llvm -target powerpc64-unknown-linux-gnu -mcpu=pwr8 -ffreestanding -DNO_WARN_X86_INTRINSICS %s \
-// RUN: -fno-discard-value-names -mllvm -disable-llvm-optzns -o - | llvm-cxxfilt -n | FileCheck %s --check-prefixes=CHECK,CHECK-BE
+// RUN: -ffp-contract=off -fno-discard-value-names -mllvm -disable-llvm-optzns -o - | llvm-cxxfilt -n | FileCheck %s --check-prefixes=CHECK,CHECK-BE
// RUN: %clang -x c++ -fsyntax-only -target powerpc64-unknown-linux-gnu -mcpu=pwr8 -ffreestanding -DNO_WARN_X86_INTRINSICS %s \
// RUN: -fno-discard-value-names -mllvm -disable-llvm-optzns
// RUN: %clang -S -emit-llvm -target powerpc64le-unknown-linux-gnu -mcpu=pwr8 -ffreestanding -DNO_WARN_X86_INTRINSICS %s \
-// RUN: -fno-discard-value-names -mllvm -disable-llvm-optzns -o - | llvm-cxxfilt -n | FileCheck %s --check-prefixes=CHECK,CHECK-LE
+// RUN: -ffp-contract=off -fno-discard-value-names -mllvm -disable-llvm-optzns -o - | llvm-cxxfilt -n | FileCheck %s --check-prefixes=CHECK,CHECK-LE
// RUN: %clang -x c++ -fsyntax-only -target powerpc64le-unknown-linux-gnu -mcpu=pwr8 -ffreestanding -DNO_WARN_X86_INTRINSICS %s \
// RUN: -fno-discard-value-names -mllvm -disable-llvm-optzns
Index: clang/test/CodeGen/ppc-emmintrin.c
===================================================================
--- clang/test/CodeGen/ppc-emmintrin.c
+++ clang/test/CodeGen/ppc-emmintrin.c
@@ -2,9 +2,9 @@
// REQUIRES: powerpc-registered-target
// RUN: %clang -S -emit-llvm -target powerpc64-unknown-linux-gnu -mcpu=pwr8 -ffreestanding -DNO_WARN_X86_INTRINSICS %s \
-// RUN: -fno-discard-value-names -mllvm -disable-llvm-optzns -o - | llvm-cxxfilt -n | FileCheck %s --check-prefixes=CHECK,CHECK-BE
+// RUN: -ffp-contract=off -fno-discard-value-names -mllvm -disable-llvm-optzns -o - | llvm-cxxfilt -n | FileCheck %s --check-prefixes=CHECK,CHECK-BE
// RUN: %clang -S -emit-llvm -target powerpc64le-unknown-linux-gnu -mcpu=pwr8 -ffreestanding -DNO_WARN_X86_INTRINSICS %s \
-// RUN: -fno-discard-value-names -mllvm -disable-llvm-optzns -o - | llvm-cxxfilt -n | FileCheck %s --check-prefixes=CHECK,CHECK-LE
+// RUN: -ffp-contract=off -fno-discard-value-names -mllvm -disable-llvm-optzns -o - | llvm-cxxfilt -n | FileCheck %s --check-prefixes=CHECK,CHECK-LE
// CHECK-BE-DAG: @_mm_movemask_pd.perm_mask = internal constant <4 x i32> <i32 -2139062144, i32 -2139062144, i32 -2139062144, i32 -2139078656>, align 16
// CHECK-BE-DAG: @_mm_shuffle_epi32.permute_selectors = internal constant [4 x i32] [i32 66051, i32 67438087, i32 134810123, i32 202182159], align 4
Index: clang/test/CodeGen/ffp-model.c
===================================================================
--- /dev/null
+++ clang/test/CodeGen/ffp-model.c
@@ -0,0 +1,52 @@
+// REQUIRES: x86-registered-target
+// RUN: %clang -S -emit-llvm -ffp-model=fast -emit-llvm %s -o - \
+// RUN: | FileCheck %s \
+// RUN: --check-prefixes=CHECK,CHECK-FAST --strict-whitespace
+
+// RUN: %clang -S -emit-llvm -ffp-model=precise %s -o - \
+// RUN: | FileCheck %s \
+// RUN: --check-prefixes=CHECK,CHECK-PRECISE --strict-whitespace
+
+// RUN: %clang -S -emit-llvm -ffp-model=strict %s -o - \
+// RUN: | FileCheck %s \
+// RUN: --check-prefixes=CHECK,CHECK-STRICT --strict-whitespace
+
+// RUN: %clang -S -emit-llvm -ffp-model=strict -ffast-math \
+// RUN: %s -o - | FileCheck %s \
+// RUN: --check-prefixes CHECK,CHECK-STRICT-FAST --strict-whitespace
+
+// RUN: %clang -S -emit-llvm -ffp-model=precise -ffast-math \
+// RUN: %s -o - | FileCheck %s \
+// RUN: --check-prefixes CHECK,CHECK-FAST1 --strict-whitespace
+
+float mymuladd(float x, float y, float z) {
+ // CHECK: define {{.*}} float @mymuladd
+ return x * y + z;
+
+ // CHECK-FAST: fmul fast float
+ // CHECK-FAST: load float, float*
+ // CHECK-FAST: fadd fast float
+
+ // CHECK-PRECISE: load float, float*
+ // CHECK-PRECISE: load float, float*
+ // CHECK-PRECISE: load float, float*
+ // CHECK-PRECISE: call float @llvm.fmuladd.f32(float {{.*}}, float {{.*}}, float {{.*}})
+
+ // CHECK-STRICT: load float, float*
+ // CHECK-STRICT: load float, float*
+ // CHECK-STRICT: call float @llvm.experimental.constrained.fmul.f32(float {{.*}}, float {{.*}}, {{.*}})
+ // CHECK-STRICT: load float, float*
+ // CHECK-STRICT: call float @llvm.experimental.constrained.fadd.f32(float {{.*}}, float {{.*}}, {{.*}})
+
+ // CHECK-STRICT-FAST: load float, float*
+ // CHECK-STRICT-FAST: load float, float*
+ // CHECK-STRICT-FAST: call fast float @llvm.experimental.constrained.fmul.f32(float {{.*}}, float {{.*}}, {{.*}})
+ // CHECK-STRICT-FAST: load float, float*
+ // CHECK-STRICT-FAST: call fast float @llvm.experimental.constrained.fadd.f32(float {{.*}}, float {{.*}}, {{.*}}
+
+ // CHECK-FAST1: load float, float*
+ // CHECK-FAST1: load float, float*
+ // CHECK-FAST1: fmul fast float {{.*}}, {{.*}}
+ // CHECK-FAST1: load float, float* {{.*}}
+ // CHECK-FAST1: fadd fast float {{.*}}, {{.*}}
+}
Index: clang/test/CodeGen/ffp-contract-option.c
===================================================================
--- clang/test/CodeGen/ffp-contract-option.c
+++ clang/test/CodeGen/ffp-contract-option.c
@@ -1,9 +1,133 @@
-// RUN: %clang_cc1 -O3 -ffp-contract=fast -triple=aarch64-apple-darwin -S -o - %s | FileCheck %s
-// REQUIRES: aarch64-registered-target
-
-float fma_test1(float a, float b, float c) {
-// CHECK: fmadd
- float x = a * b;
- float y = x + c;
- return y;
+// REQUIRES: x86-registered-target
+// RUN: %clang_cc1 -triple=x86_64 %s -emit-llvm -o - \
+// RUN:| FileCheck --check-prefixes CHECK,CHECK-DEFAULT --strict-whitespace %s
+
+// RUN: %clang_cc1 -triple=x86_64 -ffp-contract=off %s -emit-llvm -o - \
+// RUN:| FileCheck --check-prefixes CHECK,CHECK-DEFAULT --strict-whitespace %s
+
+// RUN: %clang_cc1 -triple=x86_64 -ffp-contract=on %s -emit-llvm -o - \
+// RUN:| FileCheck --check-prefixes CHECK,CHECK-ON --strict-whitespace %s
+
+// RUN: %clang_cc1 -triple=x86_64 -ffp-contract=fast %s -emit-llvm -o - \
+// RUN:| FileCheck --check-prefixes CHECK,CHECK-CONTRACTFAST --strict-whitespace %s
+
+// RUN: %clang_cc1 -triple=x86_64 -ffast-math %s -emit-llvm -o - \
+// RUN:| FileCheck --check-prefixes CHECK,CHECK-CONTRACTOFF \
+// RUN: --strict-whitespace %s
+
+// RUN: %clang_cc1 -triple=x86_64 -ffast-math -ffp-contract=off %s -emit-llvm \
+// RUN: -o - | FileCheck --check-prefixes CHECK,CHECK-CONTRACTOFF \
+// RUN: --strict-whitespace %s
+
+// RUN: %clang_cc1 -triple=x86_64 -ffast-math -ffp-contract=on %s -emit-llvm \
+// RUN: -o - | FileCheck --check-prefixes CHECK,CHECK-ONFAST \
+// RUN: --strict-whitespace %s
+
+// RUN: %clang_cc1 -triple=x86_64 -ffast-math -ffp-contract=fast %s -emit-llvm \
+// RUN: -o - | FileCheck --check-prefixes CHECK,CHECK-FASTFAST \
+// RUN: --strict-whitespace %s
+
+// RUN: %clang_cc1 -triple=x86_64 -ffp-contract=fast -ffast-math %s \
+// RUN: -emit-llvm \
+// RUN: -o - | FileCheck --check-prefixes CHECK,CHECK-FASTFAST \
+// RUN: --strict-whitespace %s
+
+// RUN: %clang_cc1 -triple=x86_64 -ffp-contract=off -fmath-errno \
+// RUN: -fno-rounding-math %s -emit-llvm -o - \
+// RUN: -o - | FileCheck --check-prefixes CHECK,CHECK-NOFAST \
+// RUN: --strict-whitespace %s
+
+// RUN: %clang -S -emit-llvm -fno-fast-math %s -o - \
+// RUN: | FileCheck %s \
+// RUN: --check-prefixes=CHECK,CHECK-FPC-ON --strict-whitespace
+
+// RUN: %clang -S -emit-llvm -ffp-contract=fast -fno-fast-math \
+// RUN: %s -o - | FileCheck %s \
+// RUN: --check-prefixes=CHECK,CHECK-FPC-ON --strict-whitespace
+
+// RUN: %clang -S -emit-llvm -ffp-contract=on -fno-fast-math \
+// RUN: %s -o - | FileCheck %s \
+// RUN: --check-prefixes=CHECK,CHECK-FPC-ON --strict-whitespace
+
+// RUN: %clang -S -emit-llvm -ffp-contract=off -fno-fast-math \
+// RUN: %s -o - | FileCheck %s \
+// RUN: --check-prefixes=CHECK,CHECK-FPC-OFF --strict-whitespace
+
+// RUN: %clang -S -emit-llvm -ffp-model=fast -fno-fast-math \
+// RUN: %s -o - | FileCheck %s \
+// RUN: --check-prefixes=CHECK,CHECK-FPC-ON --strict-whitespace
+
+// RUN: %clang -S -emit-llvm -ffp-model=precise -fno-fast-math \
+// RUN: %s -o - | FileCheck %s \
+// RUN: --check-prefixes=CHECK,CHECK-FPC-ON --strict-whitespace
+
+// RUN: %clang -S -emit-llvm -ffp-model=strict -fno-fast-math \
+// RUN: %s -o - | FileCheck %s \
+// RUN: --check-prefixes=CHECK,CHECK-FPSC-OFF --strict-whitespace
+
+// RUN: %clang -S -emit-llvm -ffast-math -fno-fast-math \
+// RUN: %s -o - | FileCheck %s \
+// RUN: --check-prefixes=CHECK,CHECK-FPC-ON --strict-whitespace
+
+float mymuladd(float x, float y, float z) {
+ // CHECK: define {{.*}}float @mymuladd
+ return x * y + z;
+ // expected-warning{{overriding '-ffp-contract=fast' option with '-ffp-contract=on'}}
+
+ // CHECK-DEFAULT: load float, float*
+ // CHECK-DEFAULT: fmul float
+ // CHECK-DEFAULT: load float, float*
+ // CHECK-DEFAULT: fadd float
+
+ // CHECK-ON: load float, float*
+ // CHECK-ON: load float, float*
+ // CHECK-ON: load float, float*
+ // CHECK-ON: call float @llvm.fmuladd.f32(float {{.*}}, float {{.*}}, float {{.*}})
+
+ // CHECK-CONTRACTFAST: load float, float*
+ // CHECK-CONTRACTFAST: load float, float*
+ // CHECK-CONTRACTFAST: fmul contract float
+ // CHECK-CONTRACTFAST: load float, float*
+ // CHECK-CONTRACTFAST: fadd contract float
+
+ // CHECK-CONTRACTOFF: load float, float*
+ // CHECK-CONTRACTOFF: load float, float*
+ // CHECK-CONTRACTOFF: fmul reassoc nnan ninf nsz arcp afn float
+ // CHECK-CONTRACTOFF: load float, float*
+ // CHECK-CONTRACTOFF: fadd reassoc nnan ninf nsz arcp afn float {{.*}}, {{.*}}
+
+ // CHECK-ONFAST: load float, float*
+ // CHECK-ONFAST: load float, float*
+ // CHECK-ONFAST: load float, float*
+ // CHECK-ONFAST: call reassoc nnan ninf nsz arcp afn float @llvm.fmuladd.f32(float {{.*}}, float {{.*}}, float {{.*}})
+
+ // CHECK-FASTFAST: load float, float*
+ // CHECK-FASTFAST: load float, float*
+ // CHECK-FASTFAST: fmul fast float
+ // CHECK-FASTFAST: load float, float*
+ // CHECK-FASTFAST: fadd fast float {{.*}}, {{.*}}
+
+ // CHECK-NOFAST: load float, float*
+ // CHECK-NOFAST: load float, float*
+ // CHECK-NOFAST: fmul float {{.*}}, {{.*}}
+ // CHECK-NOFAST: load float, float*
+ // CHECK-NOFAST: fadd float {{.*}}, {{.*}}
+
+ // CHECK-FPC-ON: load float, float*
+ // CHECK-FPC-ON: load float, float*
+ // CHECK-FPC-ON: load float, float*
+ // CHECK-FPC-ON: call float @llvm.fmuladd.f32(float {{.*}}, float {{.*}}, float {{.*}})
+
+ // CHECK-FPC-OFF: load float, float*
+ // CHECK-FPC-OFF: load float, float*
+ // CHECK-FPC-OFF: fmul float
+ // CHECK-FPC-OFF: load float, float*
+ // CHECK-FPC-OFF: fadd float {{.*}}, {{.*}}
+
+ // CHECK-FFPC-OFF: load float, float*
+ // CHECK-FFPC-OFF: load float, float*
+ // CHECK-FPSC-OFF: call float @llvm.experimental.constrained.fmul.f32(float {{.*}}, float {{.*}}, {{.*}})
+ // CHECK-FPSC-OFF: load float, float*
+ // CHECK-FPSC-OFF: [[RES:%.*]] = call float @llvm.experimental.constrained.fadd.f32(float {{.*}}, float {{.*}}, {{.*}})
+
}
Index: clang/lib/Driver/ToolChains/Clang.cpp
===================================================================
--- clang/lib/Driver/ToolChains/Clang.cpp
+++ clang/lib/Driver/ToolChains/Clang.cpp
@@ -2666,10 +2666,14 @@
llvm::DenormalMode DenormalFPMath = DefaultDenormalFPMath;
llvm::DenormalMode DenormalFP32Math = DefaultDenormalFP32Math;
- StringRef FPContract = "";
+ // CUDA and HIP don't rely on the frontend to pass an ffp-contract option.
+ // If one wasn't given by the user, don't pass it here.
+ StringRef FPContract;
+ if (!JA.isDeviceOffloading(Action::OFK_Cuda) &&
+ !JA.isOffloading(Action::OFK_HIP))
+ FPContract = "on";
bool StrictFPModel = false;
-
if (const Arg *A = Args.getLastArg(options::OPT_flimited_precision_EQ)) {
CmdArgs.push_back("-mlimit-float-precision");
CmdArgs.push_back(A->getValue());
@@ -2691,7 +2695,7 @@
ReciprocalMath = false;
SignedZeros = true;
// -fno_fast_math restores default denormal and fpcontract handling
- FPContract = "";
+ FPContract = "on";
DenormalFPMath = llvm::DenormalMode::getIEEE();
// FIXME: The target may have picked a non-IEEE default mode here based on
@@ -2711,12 +2715,10 @@
// ffp-model= is a Driver option, it is entirely rewritten into more
// granular options before being passed into cc1.
// Use the gcc option in the switch below.
- if (!FPModel.empty() && !FPModel.equals(Val)) {
+ if (!FPModel.empty() && !FPModel.equals(Val))
D.Diag(clang::diag::warn_drv_overriding_flag_option)
- << Args.MakeArgString("-ffp-model=" + FPModel)
- << Args.MakeArgString("-ffp-model=" + Val);
- FPContract = "";
- }
+ << Args.MakeArgString("-ffp-model=" + FPModel)
+ << Args.MakeArgString("-ffp-model=" + Val);
if (Val.equals("fast")) {
optID = options::OPT_ffast_math;
FPModel = Val;
@@ -2724,7 +2726,7 @@
} else if (Val.equals("precise")) {
optID = options::OPT_ffp_contract;
FPModel = Val;
- FPContract = "fast";
+ FPContract = "on";
PreciseFPModel = true;
} else if (Val.equals("strict")) {
StrictFPModel = true;
@@ -2812,9 +2814,9 @@
case options::OPT_ffp_contract: {
StringRef Val = A->getValue();
if (PreciseFPModel) {
- // -ffp-model=precise enables ffp-contract=fast as a side effect
- // the FPContract value has already been set to a string literal
- // and the Val string isn't a pertinent value.
+ // -ffp-model=precise enables ffp-contract=on.
+ // -ffp-model=precise sets PreciseFPModel to on and Val to
+ // "precise". FPContract is set.
;
} else if (Val.equals("fast") || Val.equals("on") || Val.equals("off"))
FPContract = Val;
@@ -2907,23 +2909,27 @@
AssociativeMath = false;
ReciprocalMath = false;
SignedZeros = true;
- TrappingMath = false;
- RoundingFPMath = false;
// -fno_fast_math restores default denormal and fpcontract handling
DenormalFPMath = DefaultDenormalFPMath;
DenormalFP32Math = llvm::DenormalMode::getIEEE();
- FPContract = "";
+ if (!JA.isDeviceOffloading(Action::OFK_Cuda) &&
+ !JA.isOffloading(Action::OFK_HIP))
+ if (FPContract == "fast") {
+ FPContract = "on";
+ D.Diag(clang::diag::warn_drv_overriding_flag_option)
+ << "-ffp-contract=fast"
+ << "-ffp-contract=on";
+ }
break;
}
if (StrictFPModel) {
// If -ffp-model=strict has been specified on command line but
// subsequent options conflict then emit warning diagnostic.
- if (HonorINFs && HonorNaNs &&
- !AssociativeMath && !ReciprocalMath &&
- SignedZeros && TrappingMath && RoundingFPMath &&
- (FPContract.equals("off") || FPContract.empty()) &&
- DenormalFPMath == llvm::DenormalMode::getIEEE() &&
- DenormalFP32Math == llvm::DenormalMode::getIEEE())
+ if (HonorINFs && HonorNaNs && !AssociativeMath && !ReciprocalMath &&
+ SignedZeros && TrappingMath && RoundingFPMath &&
+ DenormalFPMath == llvm::DenormalMode::getIEEE() &&
+ DenormalFP32Math == llvm::DenormalMode::getIEEE() &&
+ FPContract.equals("off"))
// OK: Current Arg doesn't conflict with -ffp-model=strict
;
else {
Index: clang/docs/UsersManual.rst
===================================================================
--- clang/docs/UsersManual.rst
+++ clang/docs/UsersManual.rst
@@ -1260,8 +1260,49 @@
Controlling Floating Point Behavior
-----------------------------------
-Clang provides a number of ways to control floating point behavior. The options
-are listed below.
+Clang provides a number of ways to control floating point behavior, including
+with command line options and source pragmas. This section
+describes the various floating point semantic modes and the corresponding options.
+
+.. csv-table:: Floating Point Semantic Modes
+ :header: "Mode", "Values"
+ :widths: 15, 30, 30
+
+ "ffp-exception-behavior", "{ignore, strict, may_trap}",
+ "fenv_access", "{off, on}", "(none)"
+ "frounding-math", "{dynamic, tonearest, downward, upward, towardzero}"
+ "ffp-contract", "{on, off, fast, fast-honor-pragmas}"
+ "fdenormal-fp-math", "{IEEE, PreserveSign, PositiveZero}"
+ "fdenormal-fp-math-fp32", "{IEEE, PreserveSign, PositiveZero}"
+ "fmath-errno", "{on, off}"
+ "fhonor-nans", "{on, off}"
+ "fhonor-infinities", "{on, off}"
+ "fsigned-zeros", "{on, off}"
+ "freciprocal-math", "{on, off}"
+ "allow_approximate_fns", "{on, off}"
+ "fassociative-math", "{on, off}"
+
+This table describes the option settings that correspond to the three
+floating point semantic models: precise (the default), strict, and fast.
+
+
+.. csv-table:: Floating Point Models
+ :header: "Mode", "Precise", "Strict", "Fast"
+ :widths: 25, 15, 15, 15
+
+ "except_behavior", "ignore", "strict", "ignore"
+ "fenv_access", "off", "on", "off"
+ "rounding_mode", "tonearest", "dynamic", "tonearest"
+ "contract", "on", "off", "fast"
+ "denormal_fp_math", "IEEE", "IEEE", "PreserveSign"
+ "denormal_fp32_math", "IEEE","IEEE", "PreserveSign"
+ "support_math_errno", "on", "on", "off"
+ "no_honor_nans", "off", "off", "on"
+ "no_honor_infinities", "off", "off", "on"
+ "no_signed_zeros", "off", "off", "on"
+ "allow_reciprocal", "off", "off", "on"
+ "allow_approximate_fns", "off", "off", "on"
+ "allow_reassociation", "off", "off", "on"
.. option:: -ffast-math
@@ -1467,7 +1508,7 @@
and ``fast``.
Details:
- * ``precise`` Disables optimizations that are not value-safe on floating-point data, although FP contraction (FMA) is enabled (``-ffp-contract=fast``). This is the default behavior.
+ * ``precise`` Disables optimizations that are not value-safe on floating-point data, although FP contraction (FMA) is enabled (``-ffp-contract=on``). This is the default behavior.
* ``strict`` Enables ``-frounding-math`` and ``-ffp-exception-behavior=strict``, and disables contractions (FMA). All of the ``-ffast-math`` enablements are disabled. Enables ``STDC FENV_ACCESS``: by default ``FENV_ACCESS`` is disabled. This option setting behaves as though ``#pragma STDC FENV_ACESS ON`` appeared at the top of the source file.
* ``fast`` Behaves identically to specifying both ``-ffast-math`` and ``ffp-contract=fast``
Index: clang/docs/ReleaseNotes.rst
===================================================================
--- clang/docs/ReleaseNotes.rst
+++ clang/docs/ReleaseNotes.rst
@@ -202,6 +202,16 @@
architecture features, but will enable certain optimizations specific to
Cortex-A57 CPUs and enable the use of a more accurate scheduling model.
+
+Floating Point Support in Clang
+-------------------------------
+- The -ffp-model=precise now implies -ffp-contract=on rather than
+ -ffp-contract=fast, and the documentation of these features has been
+ clarified. Previously, the documentation claimed that -ffp-model=precise was
+ the default, but this was incorrect because the precise model implied
+ -ffp-contract=fast, whereas the default behavior is -ffp-contract=on.
+ -ffp-model=precise is now exactly the default mode of the compiler.
+
Internal API Changes
--------------------
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