[clang] Fix -fno-unsafe-math-optimizations behavior (PR #89473)
Andy Kaylor via cfe-commits
cfe-commits at lists.llvm.org
Mon Apr 22 13:59:08 PDT 2024
https://github.com/andykaylor updated https://github.com/llvm/llvm-project/pull/89473
>From 100fc9dfb2b071877d758ce71bddeec693d986da Mon Sep 17 00:00:00 2001
From: Andy Kaylor <andrew.kaylor at intel.com>
Date: Fri, 19 Apr 2024 16:35:00 -0700
Subject: [PATCH 1/2] Fix -fno-unsafe-math-optimizations behavior
This changes the handling of -fno-unsafe-fp-math to stop having that
option imply -ftrapping-math. In gcc, -fno-unsafe-math-optimizations sets
-ftrapping-math, but that dependency is based on the fact the
-ftrapping-math is enabled by default in gcc. Because clang does not
enabled -ftrapping-math by default, there is no reason for
-fno-unsafe-math-optimizations to set it.
On the other hand, -funsafe-math-optimizations continues to imply
-fno-trapping-math because this option necessarily disables strict
exception semantics.
This fixes https://github.com/llvm/llvm-project/issues/87523
---
clang/docs/UsersManual.rst | 1 -
clang/lib/Driver/ToolChains/Clang.cpp | 2 --
clang/test/Driver/fast-math.c | 24 +++++++++++++-----------
3 files changed, 13 insertions(+), 14 deletions(-)
diff --git a/clang/docs/UsersManual.rst b/clang/docs/UsersManual.rst
index c464bc3a69adc5..2b4155d4b65a48 100644
--- a/clang/docs/UsersManual.rst
+++ b/clang/docs/UsersManual.rst
@@ -1690,7 +1690,6 @@ floating point semantic models: precise (the default), strict, and fast.
* ``-fno-associative-math``
* ``-fno-reciprocal-math``
* ``-fsigned-zeros``
- * ``-ftrapping-math``
* ``-ffp-contract=on``
* ``-fdenormal-fp-math=ieee``
diff --git a/clang/lib/Driver/ToolChains/Clang.cpp b/clang/lib/Driver/ToolChains/Clang.cpp
index 456ea74caadb00..0776d095327219 100644
--- a/clang/lib/Driver/ToolChains/Clang.cpp
+++ b/clang/lib/Driver/ToolChains/Clang.cpp
@@ -3137,8 +3137,6 @@ static void RenderFloatingPointOptions(const ToolChain &TC, const Driver &D,
ReciprocalMath = false;
SignedZeros = true;
ApproxFunc = false;
- TrappingMath = true;
- FPExceptionBehavior = "strict";
// The target may have opted to flush by default, so force IEEE.
DenormalFPMath = llvm::DenormalMode::getIEEE();
diff --git a/clang/test/Driver/fast-math.c b/clang/test/Driver/fast-math.c
index 882e81fd14d34a..ef23f88dd817ea 100644
--- a/clang/test/Driver/fast-math.c
+++ b/clang/test/Driver/fast-math.c
@@ -271,11 +271,11 @@
// RUN: 2>&1 | FileCheck --check-prefix=CHECK-NO-UNSAFE-MATH %s
// RUN: %clang -### -funsafe-math-optimizations -fno-reciprocal-math -c %s \
-// RUN: 2>&1 | FileCheck --check-prefix=CHECK-NO-UNSAFE-MATH %s
+// RUN: 2>&1 | FileCheck --check-prefix=CHECK-REASSOC-NO-UNSAFE-MATH %s
// RUN: %clang -### -funsafe-math-optimizations -fsigned-zeros -c %s 2>&1 \
// RUN: | FileCheck --check-prefix=CHECK-NO-UNSAFE-MATH %s
// RUN: %clang -### -funsafe-math-optimizations -ftrapping-math -c %s 2>&1 \
-// RUN: | FileCheck --check-prefix=CHECK-NO-UNSAFE-MATH %s
+// RUN: | FileCheck --check-prefix=CHECK-TRAPPING-NO-UNSAFE-MATH %s
// RUN: %clang -### -funsafe-math-optimizations -fno-unsafe-math-optimizations \
// RUN: -c %s 2>&1 \
// RUN: | FileCheck --check-prefix=CHECK-NO-UNSAFE-MATH %s
@@ -283,18 +283,20 @@
// RUN: | FileCheck --check-prefix=CHECK-NO-UNSAFE-MATH %s
// RUN: %clang -### -ffast-math -fno-reciprocal-math -c %s 2>&1 \
-// RUN: | FileCheck --check-prefix=CHECK-NO-UNSAFE-MATH %s
+// RUN: | FileCheck --check-prefix=CHECK-REASSOC-NO-UNSAFE-MATH %s
// RUN: %clang -### -ffast-math -fsigned-zeros -c %s 2>&1 \
// RUN: | FileCheck --check-prefix=CHECK-NO-UNSAFE-MATH %s
// RUN: %clang -### -ffast-math -ftrapping-math -c %s 2>&1 \
-// RUN: | FileCheck --check-prefix=CHECK-NO-UNSAFE-MATH %s
+// RUN: | FileCheck --check-prefix=CHECK-TRAPPING-NO-UNSAFE-MATH %s
// RUN: %clang -### -ffast-math -fno-unsafe-math-optimizations -c %s 2>&1 \
// RUN: | FileCheck --check-prefix=CHECK-NO-UNSAFE-MATH %s
// CHECK-NO-UNSAFE-MATH: "-cc1"
// CHECK-NO-UNSAFE-MATH-NOT: "-funsafe-math-optimizations"
-// CHECK-NO_UNSAFE-MATH-NOT: "-mreassociate"
+// CHECK-NO-UNSAFE-MATH-NOT: "-mreassociate"
// CHECK-NO-UNSAFE-MATH: "-o"
+// CHECK-NO-UNSAFE-MATH-NOT: "-ffp-exception-behavior=strict"
+// CHECK-TRAPPING-NO-UNSAFE-MATH: "-ffp-exception-behavior=strict"
// Reassociate is allowed because it does not require reciprocal-math.
@@ -304,8 +306,8 @@
// RUN: | FileCheck --check-prefix=CHECK-REASSOC-NO-UNSAFE-MATH %s
// CHECK-REASSOC-NO-UNSAFE-MATH: "-cc1"
-// CHECK-REASSOC-NO_UNSAFE-MATH-NOT: "-funsafe-math-optimizations"
-// CHECK-REASSOC-NO_UNSAFE-MATH: "-mreassociate"
+// CHECK-REASSOC-NO-UNSAFE-MATH-NOT: "-funsafe-math-optimizations"
+// CHECK-REASSOC-NO-UNSAFE-MATH: "-mreassociate"
// CHECK-REASSOC-NO-UNSAFE-MATH-NOT: "-funsafe-math-optimizations"
// CHECK-REASSOC-NO-UNSAFE-MATH: "-o"
@@ -318,12 +320,12 @@
// RUN: %clang -### -fassociative-math -freciprocal-math -fno-signed-zeros \
// RUN: -fno-trapping-math -ftrapping-math -c %s 2>&1 \
-// RUN: | FileCheck --check-prefix=CHECK-NO-REASSOC-NO-UNSAFE-MATH %s
+// RUN: | FileCheck --check-prefix=CHECK-NO-UNSAFE-MATH %s
// CHECK-NO-REASSOC-NO-UNSAFE-MATH: "-cc1"
-// CHECK-NO-REASSOC-NO_UNSAFE-MATH-NOT: "-funsafe-math-optimizations"
-// CHECK-NO-REASSOC-NO_UNSAFE-MATH-NOT: "-mreassociate"
-// CHECK-NO-REASSOC-NO_UNSAFE-MATH-NOT: "-funsafe-math-optimizations"
+// CHECK-NO-REASSOC-NO-UNSAFE-MATH-NOT: "-funsafe-math-optimizations"
+// CHECK-NO-REASSOC-NO-UNSAFE-MATH-NOT: "-mreassociate"
+// CHECK-NO-REASSOC-NO-UNSAFE-MATH-NOT: "-funsafe-math-optimizations"
// CHECK-NO-REASSOC-NO-UNSAFE-MATH: "-o"
>From a1ef582f6659c6bf429cce59689bacd21768e291 Mon Sep 17 00:00:00 2001
From: Andy Kaylor <andrew.kaylor at intel.com>
Date: Mon, 22 Apr 2024 13:57:48 -0700
Subject: [PATCH 2/2] Minor test clean up
---
clang/test/Driver/fast-math.c | 11 ++++++++---
1 file changed, 8 insertions(+), 3 deletions(-)
diff --git a/clang/test/Driver/fast-math.c b/clang/test/Driver/fast-math.c
index ef23f88dd817ea..e883b3c93d77df 100644
--- a/clang/test/Driver/fast-math.c
+++ b/clang/test/Driver/fast-math.c
@@ -296,7 +296,12 @@
// CHECK-NO-UNSAFE-MATH-NOT: "-mreassociate"
// CHECK-NO-UNSAFE-MATH: "-o"
// CHECK-NO-UNSAFE-MATH-NOT: "-ffp-exception-behavior=strict"
-// CHECK-TRAPPING-NO-UNSAFE-MATH: "-ffp-exception-behavior=strict"
+// CHECK-NO-UNSAFE-MATH-NOT: "-mreassociate"
+
+// CHECK-TRAPPING-NO-UNSAFE-MATH: "-cc1"
+// CHECK-TRAPPING-NO-UNSAFE-MATH-NOT: "-funsafe-math-optimizations"
+// CHECK-TRAPPING-NO-UNSAFE-MATH-SAME: "-ffp-exception-behavior=strict"
+// CHECK-TRAPPING-NO-UNSAFE-MATH-NOT: "-funsafe-math-optimizations"
// Reassociate is allowed because it does not require reciprocal-math.
@@ -307,9 +312,9 @@
// CHECK-REASSOC-NO-UNSAFE-MATH: "-cc1"
// CHECK-REASSOC-NO-UNSAFE-MATH-NOT: "-funsafe-math-optimizations"
-// CHECK-REASSOC-NO-UNSAFE-MATH: "-mreassociate"
+// CHECK-REASSOC-NO-UNSAFE-MATH-SAME: "-mreassociate"
// CHECK-REASSOC-NO-UNSAFE-MATH-NOT: "-funsafe-math-optimizations"
-// CHECK-REASSOC-NO-UNSAFE-MATH: "-o"
+// CHECK-REASSOC-NO-UNSAFE-MATH-SAME: "-o"
// In these runs, reassociate is not allowed because both no-signed-zeros and no-trapping-math are required.
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