https://github.com/andykaylor updated
https://github.com/llvm/llvm-project/pull/89477
>From 8ab931c4506f08685758a58f4cf7974c5254c3fa Mon Sep 17 00:00:00 2001
From: Andy Kaylor <andrew.kay...@intel.com>
Date: Fri, 19 Apr 2024 17:53:52 -0700
Subject: [PATCH 1/6] Clean up denormal handling with -ffp-model, -ffast-math,
etc.
This change cleans up the clang driver handling of umbrella options like
-ffast-math, -funsafe-math-optimizations, and -ffp-model, and aligns the
behavior of -ffp-model=fast with -ffast-math with regard to the linking of
crtfastmath.o.
We agreed in a previous review that the fast-math options should not
attempt to change the -fdenormal-fp-math option, which is inherently
target-specific.
The clang user's manual claims that -ffp-model=fast "behaves identically
to specifying both -ffast-math and -ffp-contract=fast." Since -ffast-math
causes crtfastmath.o to be linked if it is available, that should also
happen with -ffp-model=fast.
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.
---
clang/docs/UsersManual.rst | 4 ++--
clang/lib/Driver/ToolChain.cpp | 8 +++++++-
clang/lib/Driver/ToolChains/Clang.cpp | 4 ++++
clang/test/Driver/linux-ld.c | 3 +++
clang/test/Driver/solaris-ld.c | 3 +++
5 files changed, 19 insertions(+), 3 deletions(-)
diff --git a/clang/docs/UsersManual.rst b/clang/docs/UsersManual.rst
index d0326f01d251e0..bd6b6966ef409f 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 341d6202a9ca3c..0476ba87d07b66 100644
--- a/clang/lib/Driver/ToolChain.cpp
+++ b/clang/lib/Driver/ToolChain.cpp
@@ -1319,11 +1319,17 @@ 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)
Default = false;
+ if (A && A->getOption().getID() == options::OPT_ffp_model_EQ) {
+ StringRef Model = A->getValue();
+ if (Model != "fast")
+ Default = false;
+ }
}
// Whatever decision came as a result of the above implicit settings, either
diff --git a/clang/lib/Driver/ToolChains/Clang.cpp
b/clang/lib/Driver/ToolChains/Clang.cpp
index 651a2b5aac368b..1b1b8d6ee74801 100644
--- a/clang/lib/Driver/ToolChains/Clang.cpp
+++ b/clang/lib/Driver/ToolChains/Clang.cpp
@@ -2924,6 +2924,10 @@ 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/linux-ld.c b/clang/test/Driver/linux-ld.c
index 958e682b6c3c11..db4abbbf874eae 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
>From bf1e0133ac1be2427bf23d4abee208ff96de879e Mon Sep 17 00:00:00 2001
From: Andy Kaylor <andrew.kay...@intel.com>
Date: Wed, 24 Apr 2024 16:32:11 -0700
Subject: [PATCH 2/6] Update FP option rendering to leave denormal-fp-math
alone
---
clang/lib/Driver/ToolChains/Clang.cpp | 24 +++---------------------
1 file changed, 3 insertions(+), 21 deletions(-)
diff --git a/clang/lib/Driver/ToolChains/Clang.cpp
b/clang/lib/Driver/ToolChains/Clang.cpp
index 1b1b8d6ee74801..250dc078edf242 100644
--- a/clang/lib/Driver/ToolChains/Clang.cpp
+++ b/clang/lib/Driver/ToolChains/Clang.cpp
@@ -2743,13 +2743,11 @@ static void RenderFloatingPointOptions(const ToolChain
&TC, const Driver &D,
StringRef FPExceptionBehavior = "";
// -ffp-eval-method options: double, extended, source
StringRef FPEvalMethod = "";
- const llvm::DenormalMode DefaultDenormalFPMath =
+ llvm::DenormalMode DenormalFPMath =
TC.getDefaultDenormalModeForType(Args, JA);
- const llvm::DenormalMode DefaultDenormalFP32Math =
+ llvm::DenormalMode DenormalFP32Math =
TC.getDefaultDenormalModeForType(Args, JA, &llvm::APFloat::IEEEsingle());
- llvm::DenormalMode DenormalFPMath = DefaultDenormalFPMath;
- llvm::DenormalMode DenormalFP32Math = DefaultDenormalFP32Math;
// 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;
@@ -2899,11 +2897,6 @@ static void RenderFloatingPointOptions(const ToolChain
&TC, const Driver &D,
SignedZeros = true;
// -fno_fast_math restores default denormal and fpcontract handling
FPContract = "on";
- DenormalFPMath = llvm::DenormalMode::getIEEE();
-
- // FIXME: The target may have picked a non-IEEE default mode here based
on
- // -cl-denorms-are-zero. Should the target consider -fp-model
interaction?
- DenormalFP32Math = llvm::DenormalMode::getIEEE();
StringRef Val = A->getValue();
if (OFastEnabled && !Val.equals("fast")) {
@@ -2924,10 +2917,6 @@ 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;
@@ -3126,9 +3115,6 @@ static void RenderFloatingPointOptions(const ToolChain
&TC, const Driver &D,
TrappingMath = true;
FPExceptionBehavior = "strict";
- // The target may have opted to flush by default, so force IEEE.
- DenormalFPMath = llvm::DenormalMode::getIEEE();
- DenormalFP32Math = llvm::DenormalMode::getIEEE();
if (!JA.isDeviceOffloading(Action::OFK_Cuda) &&
!JA.isOffloading(Action::OFK_HIP)) {
if (LastSeenFfpContractOption != "") {
@@ -3158,9 +3144,7 @@ static void RenderFloatingPointOptions(const ToolChain
&TC, const Driver &D,
ReciprocalMath = false;
ApproxFunc = false;
SignedZeros = true;
- // -fno_fast_math restores default denormal and fpcontract handling
- DenormalFPMath = DefaultDenormalFPMath;
- DenormalFP32Math = llvm::DenormalMode::getIEEE();
+ // -fno_fast_math restores default fpcontract handling
if (!JA.isDeviceOffloading(Action::OFK_Cuda) &&
!JA.isOffloading(Action::OFK_HIP)) {
if (LastSeenFfpContractOption != "") {
@@ -3175,8 +3159,6 @@ static void RenderFloatingPointOptions(const ToolChain
&TC, const Driver &D,
// subsequent options conflict then emit warning diagnostic.
if (HonorINFs && HonorNaNs && !AssociativeMath && !ReciprocalMath &&
SignedZeros && TrappingMath && RoundingFPMath && !ApproxFunc &&
- DenormalFPMath == llvm::DenormalMode::getIEEE() &&
- DenormalFP32Math == llvm::DenormalMode::getIEEE() &&
FPContract.equals("off"))
// OK: Current Arg doesn't conflict with -ffp-model=strict
;
>From f1f643c02b9dd2f7cac8a3207c2d14883bbb628d Mon Sep 17 00:00:00 2001
From: Andy Kaylor <andrew.kay...@intel.com>
Date: Wed, 24 Apr 2024 16:45:26 -0700
Subject: [PATCH 3/6] User manual updates
---
clang/docs/UsersManual.rst | 15 +++++++++------
1 file changed, 9 insertions(+), 6 deletions(-)
diff --git a/clang/docs/UsersManual.rst b/clang/docs/UsersManual.rst
index bd6b6966ef409f..9c7a2bb5f650c6 100644
--- a/clang/docs/UsersManual.rst
+++ b/clang/docs/UsersManual.rst
@@ -1452,8 +1452,6 @@ 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", "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"
@@ -1462,6 +1460,14 @@ floating point semantic models: precise (the default),
strict, and fast.
"allow_approximate_fns", "off", "off", "on"
"allow_reassociation", "off", "off", "on"
+ The ``-fp-model`` option does not modify the "fdenormal-fp-math" or
+ "fdenormal-fp-math-f32" settings, but it does have an impact on whether
+ "crtfastmath.o" is linked. Because linking "crtfastmath.o" has a global
+ effect on the program, and because the global denormal handling can be
+ changed in other ways, the state of "fdenormal-fp-math" handling cannot
+ be assumed in any function based on fp-model. See :ref:`crtfastmath.o`
+ for more details.
+
.. option:: -ffast-math
Enable fast-math mode. This option lets the
@@ -1537,7 +1543,6 @@ floating point semantic models: precise (the default),
strict, and fast.
Also, this option resets following options to their target-dependent
defaults.
* ``-f[no-]math-errno``
- * ``-fdenormal-fp-math=<value>``
There is ambiguity about how ``-ffp-contract``, ``-ffast-math``,
and ``-fno-fast-math`` behave when combined. To keep the value of
@@ -1560,8 +1565,7 @@ floating point semantic models: precise (the default),
strict, and fast.
``-ffp-contract`` setting is determined by the default value of
``-ffp-contract``.
- Note: ``-fno-fast-math`` implies ``-fdenormal-fp-math=ieee``.
- ``-fno-fast-math`` causes ``crtfastmath.o`` to not be linked with code
+ Note: ``-fno-fast-math`` causes ``crtfastmath.o`` to not be linked with code
unless ``-mdaz-ftz`` is present.
.. option:: -fdenormal-fp-math=<value>
@@ -1694,7 +1698,6 @@ floating point semantic models: precise (the default),
strict, and fast.
* ``-fsigned-zeros``
* ``-ftrapping-math``
* ``-ffp-contract=on``
- * ``-fdenormal-fp-math=ieee``
There is ambiguity about how ``-ffp-contract``,
``-funsafe-math-optimizations``, and ``-fno-unsafe-math-optimizations``
>From 061485033bd50edbc35c82283c39732d0be8f673 Mon Sep 17 00:00:00 2001
From: Andy Kaylor <andrew.kay...@intel.com>
Date: Thu, 25 Apr 2024 12:09:53 -0700
Subject: [PATCH 4/6] Formatting fixes
---
clang/lib/Driver/ToolChain.cpp | 9 ++++-----
1 file changed, 4 insertions(+), 5 deletions(-)
diff --git a/clang/lib/Driver/ToolChain.cpp b/clang/lib/Driver/ToolChain.cpp
index 0476ba87d07b66..0e86bc07e0ea2c 100644
--- a/clang/lib/Driver/ToolChain.cpp
+++ b/clang/lib/Driver/ToolChain.cpp
@@ -1316,11 +1316,10 @@ bool ToolChain::isFastMathRuntimeAvailable(const
ArgList &Args,
// (to keep the linker options consistent with gcc and clang itself).
if (Default && !isOptimizationLevelFast(Args)) {
// Check if -ffast-math or -funsafe-math.
- 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_ffp_model_EQ);
+ 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_ffp_model_EQ);
if (!A || A->getOption().getID() == options::OPT_fno_fast_math ||
A->getOption().getID() == options::OPT_fno_unsafe_math_optimizations)
>From 4fc3057dbbdd1bec181d637f2aeb0fdb6e1a42ba Mon Sep 17 00:00:00 2001
From: Andy Kaylor <andrew.kay...@intel.com>
Date: Thu, 25 Apr 2024 15:17:04 -0700
Subject: [PATCH 5/6] Fix fp-model.c test and UsersManual.rst
---
clang/docs/UsersManual.rst | 14 +++++++-------
clang/test/Driver/fp-model.c | 5 ++++-
2 files changed, 11 insertions(+), 8 deletions(-)
diff --git a/clang/docs/UsersManual.rst b/clang/docs/UsersManual.rst
index 9c7a2bb5f650c6..34679a6589982b 100644
--- a/clang/docs/UsersManual.rst
+++ b/clang/docs/UsersManual.rst
@@ -1460,13 +1460,13 @@ floating point semantic models: precise (the default),
strict, and fast.
"allow_approximate_fns", "off", "off", "on"
"allow_reassociation", "off", "off", "on"
- The ``-fp-model`` option does not modify the "fdenormal-fp-math" or
- "fdenormal-fp-math-f32" settings, but it does have an impact on whether
- "crtfastmath.o" is linked. Because linking "crtfastmath.o" has a global
- effect on the program, and because the global denormal handling can be
- changed in other ways, the state of "fdenormal-fp-math" handling cannot
- be assumed in any function based on fp-model. See :ref:`crtfastmath.o`
- for more details.
+The ``-fp-model`` option does not modify the "fdenormal-fp-math" or
+"fdenormal-fp-math-f32" settings, but it does have an impact on whether
+"crtfastmath.o" is linked. Because linking "crtfastmath.o" has a global
+effect on the program, and because the global denormal handling can be
+changed in other ways, the state of "fdenormal-fp-math" handling cannot
+be assumed in any function based on fp-model. See :ref:`crtfastmath.o`
+for more details.
.. option:: -ffast-math
diff --git a/clang/test/Driver/fp-model.c b/clang/test/Driver/fp-model.c
index 74b7de7a275a76..e4e10dc174912c 100644
--- a/clang/test/Driver/fp-model.c
+++ b/clang/test/Driver/fp-model.c
@@ -64,7 +64,8 @@
// RUN: %clang -### -ffp-model=strict
-fdenormal-fp-math=preserve-sign,preserve-sign -c %s 2>&1 \
// RUN: | FileCheck --check-prefix=WARN10 %s
-// WARN10: warning: overriding '-ffp-model=strict' option with
'-fdenormal-fp-math=preserve-sign,preserve-sign' [-Woverriding-option]
+// WARN10: clang
+// WARN10-NOT: warning: overriding '-ffp-model=strict' option with
'-fdenormal-fp-math=preserve-sign,preserve-sign' [-Woverriding-option]
// RUN: %clang -### -ffp-model=fast -ffp-model=strict -c %s 2>&1 | FileCheck \
// RUN: --check-prefix=WARN11 %s
@@ -75,6 +76,7 @@
// RUN: --check-prefix=WARN12 %s
// RUN: %clang -### -ffast-math -ffp-model=strict -c %s 2>&1 | FileCheck \
// RUN: --check-prefix=WARN12 %s
+// WARN12: clang
// WARN12-NOT: warning: overriding '-ffp-model=strict' option with
'-ffp-model=strict' [-Woverriding-option]
// RUN: %clang -### -ffp-model=strict -fapprox-func -c %s 2>&1 \
@@ -129,6 +131,7 @@
// RUN: | FileCheck --check-prefix=CHECK-NO-EXCEPT %s
// RUN: %clang -### -nostdinc -ffp-model=strict -Ofast -c %s 2>&1 \
// RUN: | FileCheck --check-prefix=CHECK-NO-EXCEPT %s
+// CHECK-NO-EXCEPT: "-cc1"
// CHECK-NO-EXCEPT-NOT: "-ffp-exception-behavior=strict"
// RUN: %clang -### -nostdinc -ffp-exception-behavior=strict -c %s 2>&1 \
>From a7e4f5cf5a588b108bdb1a2635b83972881e3941 Mon Sep 17 00:00:00 2001
From: Andy Kaylor <andrew.kay...@intel.com>
Date: Fri, 26 Apr 2024 10:06:40 -0700
Subject: [PATCH 6/6] Updates based on review feedback
---
clang/docs/UsersManual.rst | 10 +++++-----
clang/test/Driver/fp-model.c | 4 ++--
2 files changed, 7 insertions(+), 7 deletions(-)
diff --git a/clang/docs/UsersManual.rst b/clang/docs/UsersManual.rst
index 34679a6589982b..1dbd0b2e3fe347 100644
--- a/clang/docs/UsersManual.rst
+++ b/clang/docs/UsersManual.rst
@@ -1460,11 +1460,11 @@ floating point semantic models: precise (the default),
strict, and fast.
"allow_approximate_fns", "off", "off", "on"
"allow_reassociation", "off", "off", "on"
-The ``-fp-model`` option does not modify the "fdenormal-fp-math" or
-"fdenormal-fp-math-f32" settings, but it does have an impact on whether
-"crtfastmath.o" is linked. Because linking "crtfastmath.o" has a global
-effect on the program, and because the global denormal handling can be
-changed in other ways, the state of "fdenormal-fp-math" handling cannot
+The ``-ffp-model`` option does not modify the ``fdenormal-fp-math``
+setting, but it does have an impact on whether ``crtfastmath.o``is
+linked. Because linking ``crtfastmath.o`` has a global effect on the
+program, and because the global denormal handling can be changed in
+other ways, the state of ``fdenormal-fp-math`` handling cannot
be assumed in any function based on fp-model. See :ref:`crtfastmath.o`
for more details.
diff --git a/clang/test/Driver/fp-model.c b/clang/test/Driver/fp-model.c
index e4e10dc174912c..a2d084b6368817 100644
--- a/clang/test/Driver/fp-model.c
+++ b/clang/test/Driver/fp-model.c
@@ -64,7 +64,7 @@
// RUN: %clang -### -ffp-model=strict
-fdenormal-fp-math=preserve-sign,preserve-sign -c %s 2>&1 \
// RUN: | FileCheck --check-prefix=WARN10 %s
-// WARN10: clang
+// WARN10: "-cc1"
// WARN10-NOT: warning: overriding '-ffp-model=strict' option with
'-fdenormal-fp-math=preserve-sign,preserve-sign' [-Woverriding-option]
// RUN: %clang -### -ffp-model=fast -ffp-model=strict -c %s 2>&1 | FileCheck \
@@ -76,7 +76,7 @@
// RUN: --check-prefix=WARN12 %s
// RUN: %clang -### -ffast-math -ffp-model=strict -c %s 2>&1 | FileCheck \
// RUN: --check-prefix=WARN12 %s
-// WARN12: clang
+// WARN12: "-cc1"
// WARN12-NOT: warning: overriding '-ffp-model=strict' option with
'-ffp-model=strict' [-Woverriding-option]
// RUN: %clang -### -ffp-model=strict -fapprox-func -c %s 2>&1 \
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