[clang] cd2c5af - Reland D74436 "Change clang option -ffp-model=precise to select ffp-contract=on""
Melanie Blower via cfe-commits
cfe-commits at lists.llvm.org
Tue Feb 18 06:55:55 PST 2020
Author: Melanie Blower
Date: 2020-02-18T06:55:36-08:00
New Revision: cd2c5af6dfd6e32ee7043894bcb42981ce99e8ac
URL: https://github.com/llvm/llvm-project/commit/cd2c5af6dfd6e32ee7043894bcb42981ce99e8ac
DIFF: https://github.com/llvm/llvm-project/commit/cd2c5af6dfd6e32ee7043894bcb42981ce99e8ac.diff
LOG: Reland D74436 "Change clang option -ffp-model=precise to select ffp-contract=on""
Change clang option -ffp-model=precise, the default, to select ffp-contract=on
The patch caused some problems for PowerPC but ibm has made
adjustments so I am resubmitting this patch. Additionally, Andy looked
at the performance regressions on LNT and it looks like a loop
unrolling decision that could be adjusted.
Reviewers: rjmccall, Andy Kaylor
Differential Revision: https://reviews.llvm.org/D74436
Added:
Modified:
clang/docs/UsersManual.rst
clang/lib/Driver/ToolChains/Clang.cpp
clang/test/CodeGen/ppc-emmintrin.c
clang/test/CodeGen/ppc-xmmintrin.c
clang/test/Driver/fp-model.c
Removed:
################################################################################
diff --git a/clang/docs/UsersManual.rst b/clang/docs/UsersManual.rst
index 856d5e34bbcc..6c8c9f802082 100644
--- a/clang/docs/UsersManual.rst
+++ b/clang/docs/UsersManual.rst
@@ -1190,8 +1190,50 @@ installed.
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
+
+ "except_behavior", "{ignore, strict, may_trap}", "ffp-exception-behavior"
+ "fenv_access", "{off, on}", "(none)"
+ "rounding_mode", "{dynamic, tonearest, downward, upward, towardzero}", "frounding-math"
+ "contract", "{on, off, fast}", "ffp-contract"
+ "denormal_fp_math", "{IEEE, PreserveSign, PositiveZero}", "fdenormal-fp-math"
+ "denormal_fp32_math", "{IEEE, PreserveSign, PositiveZero}", "fdenormal-fp-math-fp32"
+ "support_math_errno", "{on, off}", "fmath-errno"
+ "no_honor_nans", "{on, off}", "fhonor-nans"
+ "no_honor_infinities", "{on, off}", "fhonor-infinities"
+ "no_signed_zeros", "{on, off}", "fsigned-zeros"
+ "allow_reciprocal", "{on, off}", "freciprocal-math"
+ "allow_approximate_fns", "{on, off}", "(none)"
+ "allow_reassociation", "{on, off}", "fassociative-math"
+
+
+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
@@ -1385,7 +1427,7 @@ Note that floating-point operations performed as part of constant initialization
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.
* ``fast`` Behaves identically to specifying both ``-ffast-math`` and ``ffp-contract=fast``
diff --git a/clang/lib/Driver/ToolChains/Clang.cpp b/clang/lib/Driver/ToolChains/Clang.cpp
index 2585a5fa05da..d1197556aeef 100644
--- a/clang/lib/Driver/ToolChains/Clang.cpp
+++ b/clang/lib/Driver/ToolChains/Clang.cpp
@@ -2525,10 +2525,9 @@ static void RenderFloatingPointOptions(const ToolChain &TC, const Driver &D,
llvm::DenormalMode DenormalFPMath = DefaultDenormalFPMath;
llvm::DenormalMode DenormalFP32Math = DefaultDenormalFP32Math;
- StringRef FPContract = "";
+ StringRef 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());
@@ -2551,7 +2550,6 @@ static void RenderFloatingPointOptions(const ToolChain &TC, const Driver &D,
SignedZeros = true;
// -fno_fast_math restores default denormal and fpcontract handling
DenormalFPMath = DefaultDenormalFPMath;
- FPContract = "";
StringRef Val = A->getValue();
if (OFastEnabled && !Val.equals("fast")) {
// Only -ffp-model=fast is compatible with OFast, ignore.
@@ -2565,12 +2563,10 @@ static void RenderFloatingPointOptions(const ToolChain &TC, const Driver &D,
// 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 = "";
- }
if (Val.equals("fast")) {
optID = options::OPT_ffast_math;
FPModel = Val;
@@ -2578,7 +2574,7 @@ static void RenderFloatingPointOptions(const ToolChain &TC, const Driver &D,
} 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;
@@ -2664,9 +2660,11 @@ static void RenderFloatingPointOptions(const ToolChain &TC, const Driver &D,
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.
+ // When -ffp-model=precise is seen on the command line,
+ // the boolean PreciseFPModel is set to true which indicates
+ // "the current option is actually PreciseFPModel". The optID
+ // is changed to OPT_ffp_contract and FPContract is set to "on".
+ // the argument Val string is "precise": it shouldn't be checked.
;
} else if (Val.equals("fast") || Val.equals("on") || Val.equals("off"))
FPContract = Val;
@@ -2763,7 +2761,7 @@ static void RenderFloatingPointOptions(const ToolChain &TC, const Driver &D,
// -fno_fast_math restores default denormal and fpcontract handling
DenormalFPMath = DefaultDenormalFPMath;
DenormalFP32Math = DefaultDenormalFP32Math;
- FPContract = "";
+ FPContract = "on";
break;
}
if (StrictFPModel) {
@@ -2773,7 +2771,7 @@ static void RenderFloatingPointOptions(const ToolChain &TC, const Driver &D,
if (HonorINFs && HonorNaNs &&
!AssociativeMath && !ReciprocalMath &&
SignedZeros && TrappingMath && RoundingFPMath &&
- (FPContract.equals("off") || FPContract.empty()))
+ FPContract.equals("off"))
// OK: Current Arg doesn't conflict with -ffp-model=strict
;
else {
diff --git a/clang/test/CodeGen/ppc-emmintrin.c b/clang/test/CodeGen/ppc-emmintrin.c
index 631b6c9d2614..c14b2dd210f8 100644
--- a/clang/test/CodeGen/ppc-emmintrin.c
+++ b/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
diff --git a/clang/test/CodeGen/ppc-xmmintrin.c b/clang/test/CodeGen/ppc-xmmintrin.c
index e9466b32257f..d7499cbedc48 100644
--- a/clang/test/CodeGen/ppc-xmmintrin.c
+++ b/clang/test/CodeGen/ppc-xmmintrin.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
#include <xmmintrin.h>
diff --git a/clang/test/Driver/fp-model.c b/clang/test/Driver/fp-model.c
index 8bf53f6d997b..de83e4e4c913 100644
--- a/clang/test/Driver/fp-model.c
+++ b/clang/test/Driver/fp-model.c
@@ -1,85 +1,87 @@
// Test that incompatible combinations of -ffp-model= options
// and other floating point options get a warning diagnostic.
-//
-// REQUIRES: clang-driver
-// RUN: %clang -### -ffp-model=fast -ffp-contract=off -c %s 2>&1 \
+// RUN: %clang -target x86_64 -### -ffp-model=fast -ffp-contract=off -c %s 2>&1 \
// RUN: | FileCheck --check-prefix=WARN %s
// WARN: warning: overriding '-ffp-model=fast' option with '-ffp-contract=off' [-Woverriding-t-option]
-// RUN: %clang -### -ffp-model=fast -ffp-contract=on -c %s 2>&1 \
+// RUN: %clang -target x86_64 -### -ffp-model=fast -ffp-contract=on -c %s 2>&1 \
// RUN: | FileCheck --check-prefix=WARN1 %s
// WARN1: warning: overriding '-ffp-model=fast' option with '-ffp-contract=on' [-Woverriding-t-option]
-// RUN: %clang -### -ffp-model=strict -fassociative-math -c %s 2>&1 \
+// RUN: %clang -target x86_64 -### -ffp-model=strict -fassociative-math -c %s 2>&1 \
// RUN: | FileCheck --check-prefix=WARN2 %s
// WARN2: warning: overriding '-ffp-model=strict' option with '-fassociative-math' [-Woverriding-t-option]
-// RUN: %clang -### -ffp-model=strict -ffast-math -c %s 2>&1 \
+// RUN: %clang -target x86_64 -### -ffp-model=strict -ffast-math -c %s 2>&1 \
// RUN: | FileCheck --check-prefix=WARN3 %s
// WARN3: warning: overriding '-ffp-model=strict' option with '-ffast-math' [-Woverriding-t-option]
-// RUN: %clang -### -ffp-model=strict -ffinite-math-only -c %s 2>&1 \
+// RUN: %clang -target x86_64 -### -ffp-model=strict -ffinite-math-only -c %s 2>&1 \
// RUN: | FileCheck --check-prefix=WARN4 %s
// WARN4: warning: overriding '-ffp-model=strict' option with '-ffinite-math-only' [-Woverriding-t-option]
-// RUN: %clang -### -ffp-model=strict -ffp-contract=fast -c %s 2>&1 \
+// RUN: %clang -target x86_64 -### -ffp-model=strict -ffp-contract=fast -c %s 2>&1 \
// RUN: | FileCheck --check-prefix=WARN5 %s
// WARN5: warning: overriding '-ffp-model=strict' option with '-ffp-contract=fast' [-Woverriding-t-option]
-// RUN: %clang -### -ffp-model=strict -ffp-contract=on -c %s 2>&1 \
+// RUN: %clang -target x86_64 -### -ffp-model=strict -ffp-contract=fast -c %s 2>&1 \
+// RUN: | FileCheck --check-prefix=WARN6 %s
+// WARN6: warning: overriding '-ffp-model=strict' option with '-ffp-contract=fast' [-Woverriding-t-option]
+
+// RUN: %clang -target x86_64 -### -ffp-model=strict -ffp-contract=on -c %s 2>&1 \
// RUN: | FileCheck --check-prefix=WARN7 %s
// WARN7: warning: overriding '-ffp-model=strict' option with '-ffp-contract=on' [-Woverriding-t-option]
-// RUN: %clang -### -ffp-model=strict -fno-honor-infinities -c %s 2>&1 \
+// RUN: %clang -target x86_64 -### -ffp-model=strict -fno-honor-infinities -c %s 2>&1 \
// RUN: | FileCheck --check-prefix=WARN8 %s
// WARN8: warning: overriding '-ffp-model=strict' option with '-fno-honor-infinities' [-Woverriding-t-option]
-// RUN: %clang -### -ffp-model=strict -fno-honor-nans -c %s 2>&1 \
+// RUN: %clang -target x86_64 -### -ffp-model=strict -fno-honor-nans -c %s 2>&1 \
// RUN: | FileCheck --check-prefix=WARN9 %s
// WARN9: warning: overriding '-ffp-model=strict' option with '-fno-honor-nans' [-Woverriding-t-option]
-// RUN: %clang -### -ffp-model=strict -fno-rounding-math -c %s 2>&1 \
+// RUN: %clang -target x86_64 -### -ffp-model=strict -fno-rounding-math -c %s 2>&1 \
// RUN: | FileCheck --check-prefix=WARNa %s
// WARNa: warning: overriding '-ffp-model=strict' option with '-fno-rounding-math' [-Woverriding-t-option]
-// RUN: %clang -### -ffp-model=strict -fno-signed-zeros -c %s 2>&1 \
+// RUN: %clang -target x86_64 -### -ffp-model=strict -fno-signed-zeros -c %s 2>&1 \
// RUN: | FileCheck --check-prefix=WARNb %s
// WARNb: warning: overriding '-ffp-model=strict' option with '-fno-signed-zeros' [-Woverriding-t-option]
-// RUN: %clang -### -ffp-model=strict -fno-trapping-math -c %s 2>&1 \
+// RUN: %clang -target x86_64 -### -ffp-model=strict -fno-trapping-math -c %s 2>&1 \
// RUN: | FileCheck --check-prefix=WARNc %s
// WARNc: warning: overriding '-ffp-model=strict' option with '-fno-trapping-math' [-Woverriding-t-option]
-// RUN: %clang -### -ffp-model=strict -freciprocal-math -c %s 2>&1 \
+// RUN: %clang -target x86_64 -### -ffp-model=strict -freciprocal-math -c %s 2>&1 \
// RUN: | FileCheck --check-prefix=WARNd %s
// WARNd: warning: overriding '-ffp-model=strict' option with '-freciprocal-math' [-Woverriding-t-option]
-// RUN: %clang -### -ffp-model=strict -funsafe-math-optimizations -c %s 2>&1 \
+// RUN: %clang -target x86_64 -### -ffp-model=strict -funsafe-math-optimizations -c %s 2>&1 \
// RUN: | FileCheck --check-prefix=WARNe %s
// WARNe: warning: overriding '-ffp-model=strict' option with '-funsafe-math-optimizations' [-Woverriding-t-option]
-// RUN: %clang -### -ffp-model=strict -Ofast -c %s 2>&1 \
+// RUN: %clang -target x86_64 -### -ffp-model=strict -Ofast -c %s 2>&1 \
// RUN: | FileCheck --check-prefix=WARNf %s
// WARNf: warning: overriding '-ffp-model=strict' option with '-Ofast' [-Woverriding-t-option]
-// RUN: %clang -### -c %s 2>&1 \
+// RUN: %clang -target x86_64 -### -c %s 2>&1 \
// RUN: | FileCheck --check-prefix=CHECK-NOROUND %s
// CHECK-NOROUND: "-cc1"
// CHECK-NOROUND: "-fno-rounding-math"
-// RUN: %clang -### -frounding-math -c %s 2>&1 \
+// RUN: %clang -target x86_64 -### -frounding-math -c %s 2>&1 \
// RUN: | FileCheck --check-prefix=CHECK-ROUND --implicit-check-not ffp-exception-behavior=strict %s
// CHECK-ROUND: "-cc1"
// CHECK-ROUND: "-frounding-math"
-// RUN: %clang -### -ftrapping-math -c %s 2>&1 \
+// RUN: %clang -target x86_64 -### -ftrapping-math -c %s 2>&1 \
// RUN: | FileCheck --check-prefix=CHECK-TRAP %s
// CHECK-TRAP: "-cc1"
// CHECK-TRAP: "-ftrapping-math"
// CHECK-TRAP: "-ffp-exception-behavior=strict"
-// RUN: %clang -### -nostdinc -ffp-model=fast -c %s 2>&1 \
+// RUN: %clang -target x86_64 -### -nostdinc -ffp-model=fast -c %s 2>&1 \
// RUN: | FileCheck --check-prefix=CHECK-FPM-FAST %s
// CHECK-FPM-FAST: "-cc1"
// CHECK-FPM-FAST: "-menable-no-infs"
@@ -93,41 +95,41 @@
// CHECK-FPM-FAST: "-ffast-math"
// CHECK-FPM-FAST: "-ffinite-math-only"
-// RUN: %clang -### -nostdinc -ffp-model=precise -c %s 2>&1 \
+// RUN: %clang -target x86_64 -### -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 \
+// RUN: %clang -target x86_64 -### -nostdinc -ffp-model=strict -c %s 2>&1 \
// RUN: | FileCheck --check-prefix=CHECK-FPM-STRICT %s
// CHECK-FPM-STRICT: "-cc1"
// CHECK-FPM-STRICT: "-ftrapping-math"
+// CHECK-FPM-STRICT: "-ffp-contract=off"
// CHECK-FPM-STRICT: "-frounding-math"
// CHECK-FPM-STRICT: "-ffp-exception-behavior=strict"
-// RUN: %clang -### -nostdinc -ftrapping-math -ffp-exception-behavior=ignore -c %s 2>&1 \
+// RUN: %clang -target x86_64 -### -nostdinc -ftrapping-math -ffp-exception-behavior=ignore -c %s 2>&1 \
// RUN: | FileCheck --check-prefix=CHECK-TRAP-IGNORE %s
// CHECK-TRAP-IGNORE: "-cc1"
// CHECK-TRAP-IGNORE: "-fno-rounding-math"
// CHECK-TRAP-IGNORE: "-ffp-exception-behavior=ignore"
-// RUN: %clang -### -nostdinc -ffp-exception-behavior=strict -c %s 2>&1 \
+// RUN: %clang -target x86_64 -### -nostdinc -ffp-exception-behavior=strict -c %s 2>&1 \
// RUN: | FileCheck --check-prefix=CHECK-FEB-STRICT %s
// CHECK-FEB-STRICT: "-cc1"
// CHECK-FEB-STRICT: "-fno-rounding-math"
// CHECK-FEB-STRICT: "-ffp-exception-behavior=strict"
-// RUN: %clang -### -nostdinc -ffp-exception-behavior=maytrap -c %s 2>&1 \
+// RUN: %clang -target x86_64 -### -nostdinc -ffp-exception-behavior=maytrap -c %s 2>&1 \
// RUN: | FileCheck --check-prefix=CHECK-FEB-MAYTRAP %s
// CHECK-FEB-MAYTRAP: "-cc1"
// CHECK-FEB-MAYTRAP: "-fno-rounding-math"
// CHECK-FEB-MAYTRAP: "-ffp-exception-behavior=maytrap"
-// RUN: %clang -### -nostdinc -ffp-exception-behavior=ignore -c %s 2>&1 \
+// RUN: %clang -target x86_64 -### -nostdinc -ffp-exception-behavior=ignore -c %s 2>&1 \
// RUN: | FileCheck --check-prefix=CHECK-FEB-IGNORE %s
// CHECK-FEB-IGNORE: "-cc1"
// CHECK-FEB-IGNORE: "-fno-rounding-math"
// CHECK-FEB-IGNORE: "-ffp-exception-behavior=ignore"
-
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