[Driver, CodeGen] rename options to disable an FP cast optimization
As suggested in the post-commit thread for rL331056, we should match these
clang options with the established vocabulary of the corresponding sanitizer
option. Also, the use of 'strict' is well-known for these kinds of knobs,
and we can improve the descriptive text in the docs.
So this intends to match the logic of D46135 but only change the words.
Matching LLVM commit to match this spelling of the attribute to follow shortly.
Differential Revision: https://reviews.llvm.org/D46236
llvm-svn: 331209
diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index b6672bd..ba7898b 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -89,14 +89,13 @@
New Compiler Flags
------------------
-- :option:`-ffp-cast-overflow-workaround` and
- :option:`-fno-fp-cast-overflow-workaround`
- enable (disable) a workaround for code that casts floating-point values to
- integers and back to floating-point. If the floating-point value is not
- representable in the intermediate integer type, the code is incorrect
- according to the language standard. This flag will attempt to generate code
- as if the result of an overflowing conversion matches the overflowing behavior
- of a target's native float-to-int conversion instructions.
+- :option:`-fstrict-float-cast-overflow` and
+ :option:`-fno-strict-float-cast-overflow` -
+ When a floating-point value is not representable in a destination integer
+ type, the code has undefined behavior according to the language standard.
+ By default, Clang will not guarantee any particular result in that case.
+ With the 'no-strict' option, Clang attempts to match the overflowing behavior
+ of the target's native float-to-int conversion instructions.
- ...
diff --git a/clang/docs/UsersManual.rst b/clang/docs/UsersManual.rst
index 7425d2a..729adfd 100644
--- a/clang/docs/UsersManual.rst
+++ b/clang/docs/UsersManual.rst
@@ -1255,15 +1255,13 @@
flushed-to-zero number is preserved in the sign of 0, denormals are
flushed to positive zero, respectively.
-.. option:: -f[no-]fp-cast-overflow-workaround
+.. option:: -f[no-]strict-float-cast-overflow
- Enable a workaround for code that casts floating-point values to
- integers and back to floating-point. If the floating-point value
- is not representable in the intermediate integer type, the code is
- incorrect according to the language standard. This flag will attempt
- to generate code as if the result of an overflowing conversion matches
- the overflowing behavior of a target's native float-to-int conversion
- instructions.
+ When a floating-point value is not representable in a destination integer
+ type, the code has undefined behavior according to the language standard.
+ By default, Clang will not guarantee any particular result in that case.
+ With the 'no-strict' option, Clang attempts to match the overflowing behavior
+ of the target's native float-to-int conversion instructions.
.. option:: -fwhole-program-vtables
diff --git a/clang/include/clang/Driver/Options.td b/clang/include/clang/Driver/Options.td
index f18a3b1..3a5d58a 100644
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -1029,10 +1029,12 @@
Flags<[CC1Option]>, HelpText<"Form fused FP ops (e.g. FMAs): fast (everywhere)"
" | on (according to FP_CONTRACT pragma, default) | off (never fuse)">, Values<"fast,on,off">;
-def ffp_cast_overflow_workaround : Flag<["-"],
- "ffp-cast-overflow-workaround">, Group<f_Group>, Flags<[CC1Option]>;
-def fno_fp_cast_overflow_workaround : Flag<["-"],
- "fno-fp-cast-overflow-workaround">, Group<f_Group>, Flags<[CC1Option]>;
+def fstrict_float_cast_overflow : Flag<["-"],
+ "fstrict-float-cast-overflow">, Group<f_Group>, Flags<[CC1Option]>,
+ HelpText<"Assume that overflowing float-to-int casts are undefined (default)">;
+def fno_strict_float_cast_overflow : Flag<["-"],
+ "fno-strict-float-cast-overflow">, Group<f_Group>, Flags<[CC1Option]>,
+ HelpText<"Relax language rules and try to match the behavior of the target's native float-to-int conversion instructions">;
def ffor_scope : Flag<["-"], "ffor-scope">, Group<f_Group>;
def fno_for_scope : Flag<["-"], "fno-for-scope">, Group<f_Group>;
diff --git a/clang/include/clang/Frontend/CodeGenOptions.def b/clang/include/clang/Frontend/CodeGenOptions.def
index 1747aa7..52e10b3 100644
--- a/clang/include/clang/Frontend/CodeGenOptions.def
+++ b/clang/include/clang/Frontend/CodeGenOptions.def
@@ -137,10 +137,10 @@
CODEGENOPT(FlushDenorm , 1, 0) ///< Allow FP denorm numbers to be flushed to zero
CODEGENOPT(CorrectlyRoundedDivSqrt, 1, 0) ///< -cl-fp32-correctly-rounded-divide-sqrt
-/// Disable a float-to-int-to-float cast optimization. This attempts to generate
-/// code as if the result of an overflowing conversion matches the overflowing
-/// behavior of a target's native float-to-int conversion instructions.
-CODEGENOPT(FPCastOverflowWorkaround, 1, 0)
+/// When false, this attempts to generate code as if the result of an
+/// overflowing conversion matches the overflowing behavior of a target's native
+/// float-to-int conversion instructions.
+CODEGENOPT(StrictFloatCastOverflow, 1, 1)
CODEGENOPT(UniformWGSize , 1, 0) ///< -cl-uniform-work-group-size
CODEGENOPT(NoZeroInitializedInBSS , 1, 0) ///< -fno-zero-initialized-in-bss.
diff --git a/clang/lib/CodeGen/CGCall.cpp b/clang/lib/CodeGen/CGCall.cpp
index da2ff14..89f86ca 100644
--- a/clang/lib/CodeGen/CGCall.cpp
+++ b/clang/lib/CodeGen/CGCall.cpp
@@ -1727,8 +1727,10 @@
FuncAttrs.addAttribute("no-trapping-math",
llvm::toStringRef(CodeGenOpts.NoTrappingMath));
- if (CodeGenOpts.FPCastOverflowWorkaround)
- FuncAttrs.addAttribute("fp-cast-overflow-workaround", "true");
+ // Strict (compliant) code is the default, so only add this attribute to
+ // indicate that we are trying to workaround a problem case.
+ if (!CodeGenOpts.StrictFloatCastOverflow)
+ FuncAttrs.addAttribute("strict-float-cast-overflow", "false");
// TODO: Are these all needed?
// unsafe/inf/nan/nsz are handled by instruction-level FastMathFlags.
diff --git a/clang/lib/Driver/ToolChains/Clang.cpp b/clang/lib/Driver/ToolChains/Clang.cpp
index 3dc657e..331b4be 100644
--- a/clang/lib/Driver/ToolChains/Clang.cpp
+++ b/clang/lib/Driver/ToolChains/Clang.cpp
@@ -2243,9 +2243,9 @@
}
// Disable a codegen optimization for floating-point casts.
- if (Args.hasFlag(options::OPT_ffp_cast_overflow_workaround,
- options::OPT_fno_fp_cast_overflow_workaround, false))
- CmdArgs.push_back("-ffp-cast-overflow-workaround");
+ if (Args.hasFlag(options::OPT_fno_strict_float_cast_overflow,
+ options::OPT_fstrict_float_cast_overflow, false))
+ CmdArgs.push_back("-fno-strict-float-cast-overflow");
}
static void RenderAnalyzerOptions(const ArgList &Args, ArgStringList &CmdArgs,
diff --git a/clang/lib/Frontend/CompilerInvocation.cpp b/clang/lib/Frontend/CompilerInvocation.cpp
index 9ef4ad7..44f29ba 100644
--- a/clang/lib/Frontend/CompilerInvocation.cpp
+++ b/clang/lib/Frontend/CompilerInvocation.cpp
@@ -699,7 +699,8 @@
Opts.Reciprocals = Args.getAllArgValues(OPT_mrecip_EQ);
Opts.ReciprocalMath = Args.hasArg(OPT_freciprocal_math);
Opts.NoTrappingMath = Args.hasArg(OPT_fno_trapping_math);
- Opts.FPCastOverflowWorkaround = Args.hasArg(OPT_ffp_cast_overflow_workaround);
+ Opts.StrictFloatCastOverflow =
+ !Args.hasArg(OPT_fno_strict_float_cast_overflow);
Opts.NoZeroInitializedInBSS = Args.hasArg(OPT_mno_zero_initialized_in_bss);
Opts.NumRegisterParameters = getLastArgIntValue(Args, OPT_mregparm, 0, Diags);
diff --git a/clang/test/CodeGen/no-junk-ftrunc.c b/clang/test/CodeGen/no-junk-ftrunc.c
index ff3f640..a645d96 100644
--- a/clang/test/CodeGen/no-junk-ftrunc.c
+++ b/clang/test/CodeGen/no-junk-ftrunc.c
@@ -1,12 +1,16 @@
-// RUN: %clang_cc1 -S -ffp-cast-overflow-workaround %s -emit-llvm -o - | FileCheck %s
-// CHECK-LABEL: main
-// CHECK: attributes #0 = {{.*}}"fp-cast-overflow-workaround"="true"{{.*}}
+// RUN: %clang_cc1 -S -fno-strict-float-cast-overflow %s -emit-llvm -o - | FileCheck %s --check-prefix=NOSTRICT
+// NOSTRICT-LABEL: main
+// NOSTRICT: attributes #0 = {{.*}}"strict-float-cast-overflow"="false"{{.*}}
// The workaround attribute is not applied by default.
+// RUN: %clang_cc1 -S %s -fstrict-float-cast-overflow -emit-llvm -o - | FileCheck %s --check-prefix=STRICT
+// STRICT-LABEL: main
+// STRICT-NOT: strict-float-cast-overflow
+
// RUN: %clang_cc1 -S %s -emit-llvm -o - | FileCheck %s --check-prefix=DEFAULT
// DEFAULT-LABEL: main
-// DEFAULT-NOT: fp-cast-overflow-workaround
+// DEFAULT-NOT: strict-float-cast-overflow
int main() {
return 0;
diff --git a/clang/test/Driver/fast-math.c b/clang/test/Driver/fast-math.c
index e1e07f3..57e5d2c 100644
--- a/clang/test/Driver/fast-math.c
+++ b/clang/test/Driver/fast-math.c
@@ -289,25 +289,25 @@
// CHECK-NO-TRAPPING-MATH: "-fno-trapping-math"
// This isn't fast-math, but the option is handled in the same place as other FP params.
-// Last option wins, and the flag is *not* passed by default.
+// Last option wins, and strict behavior is assumed by default.
-// RUN: %clang -### -ffp-cast-overflow-workaround -c %s 2>&1 \
+// RUN: %clang -### -fno-strict-float-cast-overflow -c %s 2>&1 \
// RUN: | FileCheck --check-prefix=CHECK-FPOV-WORKAROUND %s
// CHECK-FPOV-WORKAROUND: "-cc1"
-// CHECK-FPOV-WORKAROUND: "-ffp-cast-overflow-workaround"
+// CHECK-FPOV-WORKAROUND: "-fno-strict-float-cast-overflow"
// RUN: %clang -### -c %s 2>&1 \
// RUN: | FileCheck --check-prefix=CHECK-FPOV-WORKAROUND-DEFAULT %s
// CHECK-FPOV-WORKAROUND-DEFAULT: "-cc1"
-// CHECK-FPOV-WORKAROUND-DEFAULT-NOT: "-ffp-cast-overflow-workaround"
+// CHECK-FPOV-WORKAROUND-DEFAULT-NOT: "strict-float-cast-overflow"
-// RUN: %clang -### -fno-fp-cast-overflow-workaround -c %s 2>&1 \
+// RUN: %clang -### -fstrict-float-cast-overflow -c %s 2>&1 \
// RUN: | FileCheck --check-prefix=CHECK-NO-FPOV-WORKAROUND %s
// CHECK-NO-FPOV-WORKAROUND: "-cc1"
-// CHECK-NO-FPOV-WORKAROUND-NOT: "-ffp-cast-overflow-workaround"
+// CHECK-NO-FPOV-WORKAROUND-NOT: "strict-float-cast-overflow"
-// RUN: %clang -### -ffp-cast-overflow-workaround -fno-fp-cast-overflow-workaround -c %s 2>&1 \
+// RUN: %clang -### -fno-strict-float-cast-overflow -fstrict-float-cast-overflow -c %s 2>&1 \
// RUN: | FileCheck --check-prefix=CHECK-NO-FPOV-WORKAROUND-OVERRIDE %s
// CHECK-NO-FPOV-WORKAROUND-OVERRIDE: "-cc1"
-// CHECK-NO-FPOV-WORKAROUND-OVERRIDE-NOT: "-ffp-cast-overflow-workaround"
+// CHECK-NO-FPOV-WORKAROUND-OVERRIDE-NOT: "strict-float-cast-overflow"