Hi hfinkel, andreadb, alexr,
This is the front-end counterpart to D8982.
The option parsing implementation is based on maintaining compatibility with
gcc; gcc documentation for this flag:
https://gcc.gnu.org/onlinedocs/gcc-4.9.2/gcc/i386-and-x86-64-Options.html#index-mrecip_003dopt-1627
Note that PowerPC could have its own -mrecip options if further compatibility
is desired:
https://gcc.gnu.org/onlinedocs/gcc-4.9.2/gcc/RS_002f6000-and-PowerPC-Options.html#index-mrecip-2289
With this flag in place, customers will have fine-grain control over reciprocal
estimate codegen, so we may choose to align with gcc's optimization behavior
for that. Eg, LLVM could generate reciprocal square root by default when
-ffast-math is on. This was requested in PR21385 (
https://llvm.org/bugs/show_bug.cgi?id=21385 ).
http://reviews.llvm.org/D8989
Files:
include/clang/Driver/Options.td
lib/Driver/Tools.cpp
test/Driver/x86_features.c
EMAIL PREFERENCES
http://reviews.llvm.org/settings/panel/emailpreferences/
Index: include/clang/Driver/Options.td
===================================================================
--- include/clang/Driver/Options.td
+++ include/clang/Driver/Options.td
@@ -1320,6 +1320,8 @@
def mno_implicit_float : Flag<["-"], "mno-implicit-float">, Group<m_Group>,
HelpText<"Don't generate implicit floating point instructions">;
def mimplicit_float : Flag<["-"], "mimplicit-float">, Group<m_Group>;
+def mrecip : Flag<["-"], "mrecip">, Group<m_Group>;
+def mrecip_EQ : CommaJoined<["-"], "mrecip=">, Group<m_Group>;
def msse2 : Flag<["-"], "msse2">, Group<m_x86_Features_Group>;
def msse3 : Flag<["-"], "msse3">, Group<m_x86_Features_Group>;
def msse4a : Flag<["-"], "msse4a">, Group<m_x86_Features_Group>;
Index: lib/Driver/Tools.cpp
===================================================================
--- lib/Driver/Tools.cpp
+++ lib/Driver/Tools.cpp
@@ -1578,6 +1578,71 @@
CmdArgs.push_back(Args.MakeArgString(Twine("-plugin-opt=mcpu=") + CPU));
}
+// The -mrecip flag is not unique to x86, but it sets x86-specific target
+// features. It requires processing of many optional parameters.
+static void ParseRecip(const Driver &D, const ArgList &Args,
+ std::vector<const char *> &Features) {
+ Arg *A = Args.getLastArg(options::OPT_mrecip, options::OPT_mrecip_EQ);
+ if (!A)
+ return;
+
+ const char *OptionStrings[] = {
+ "div",
+ "vec-div",
+ "sqrt",
+ "vec-sqrt"
+ };
+
+ std::string Prefix = "+recip-";
+
+ unsigned NumOptions = A->getNumValues();
+ unsigned NumStrings = llvm::array_lengthof(OptionStrings);
+
+ if (NumOptions > NumStrings) {
+ D.Diag(diag::err_drv_argument_not_allowed_with)
+ << A->getOption().getName() << "Too many options specified.";
+ }
+
+ // If "none" is specified, negate the prefix and proceed as if no option was
+ // specified.
+ if (NumOptions == 1 && strcmp(A->getValue(0), "none") == 0) {
+ Prefix[0] = '-';
+ NumOptions = 0;
+ }
+
+ // If "all", "default" or no options are specified, set all features.
+ if (NumOptions == 0 ||
+ (NumOptions == 1 && strcmp(A->getValue(0), "all") == 0) ||
+ (NumOptions == 1 && strcmp(A->getValue(0), "default") == 0)) {
+ for (unsigned i = 0; i != NumStrings ; ++i)
+ Features.push_back(Args.MakeArgString(Prefix + OptionStrings[i]));
+ return;
+ }
+
+ // Each reciprocal type may be enabled or disabled ("!") individually.
+ for (unsigned i = 0; i != NumOptions; ++i) {
+ const char *Value = A->getValue(i);
+ // Ignore the '!' in string comparison.
+ bool IsNegative = (Value[0] == '!');
+ if (IsNegative)
+ Value++;
+
+ bool Found = false;
+ for (unsigned j = 0; j != NumStrings; ++j) {
+ if (strcmp(OptionStrings[j], Value) == 0) {
+ Prefix[0] = IsNegative ? '-' : '+';
+ Features.push_back(Args.MakeArgString(Prefix + OptionStrings[j]));
+ Found = true;
+ break;
+ }
+ }
+ if (!Found) {
+ D.Diag(diag::err_drv_unsupported_option_argument) <<
+ A->getOption().getName() << Value;
+ }
+ }
+}
+
static void getX86TargetFeatures(const Driver &D, const llvm::Triple &Triple,
const ArgList &Args,
std::vector<const char *> &Features) {
@@ -1655,6 +1720,8 @@
Features.push_back(Args.MakeArgString((IsNegative ? "-" : "+") + Name));
}
+
+ ParseRecip(D, Args, Features);
}
void Clang::AddX86TargetArgs(const ArgList &Args,
Index: test/Driver/x86_features.c
===================================================================
--- test/Driver/x86_features.c
+++ test/Driver/x86_features.c
@@ -5,3 +5,48 @@
// Test that we don't produce an error with -mieee-fp.
// RUN: %clang -### %s -mieee-fp -S 2>&1 | FileCheck --check-prefix=IEEE %s
// IEEE-NOT: error: unknown argument
+
+// Test various options for the -mrecip flag.
+
+// RUN: %clang -target i386-unknown-unknown -### -S %s -mrecip 2>&1 | FileCheck --check-prefix=RECIP0 %s
+// RECIP0: "-target-feature" "+recip-div" "-target-feature" "+recip-vec-div" "-target-feature" "+recip-sqrt" "-target-feature" "+recip-vec-sqrt"
+
+// RUN: %clang -target i386-unknown-unknown -### -S %s -mrecip=all 2>&1 | FileCheck --check-prefix=RECIP1 %s
+// RECIP1: "-target-feature" "+recip-div" "-target-feature" "+recip-vec-div" "-target-feature" "+recip-sqrt" "-target-feature" "+recip-vec-sqrt"
+
+// RUN: %clang -target i386-unknown-unknown -### -S %s -mrecip=default 2>&1 | FileCheck --check-prefix=RECIP2 %s
+// RECIP2: "-target-feature" "+recip-div" "-target-feature" "+recip-vec-div" "-target-feature" "+recip-sqrt" "-target-feature" "+recip-vec-sqrt"
+
+// RUN: %clang -target i386-unknown-unknown -### -S %s -mrecip=none 2>&1 | FileCheck --check-prefix=RECIP3 %s
+// RECIP3: "-target-feature" "-recip-div" "-target-feature" "-recip-vec-div" "-target-feature" "-recip-sqrt" "-target-feature" "-recip-vec-sqrt"
+
+// RUN: %clang -target i386-unknown-unknown -### -S %s -mrecip=div,sqrt,vec-div,vec-sqrt 2>&1 | FileCheck --check-prefix=RECIP4 %s
+// RECIP4: "-target-feature" "+recip-div" "-target-feature" "+recip-sqrt" "-target-feature" "+recip-vec-div" "-target-feature" "+recip-vec-sqrt"
+
+// RUN: %clang -target i386-unknown-unknown -### -S %s -mrecip=div 2>&1 | FileCheck --check-prefix=RECIP5 %s
+// RECIP5: "-target-feature" "+recip-div"
+
+// RUN: %clang -target i386-unknown-unknown -### -S %s -mrecip=vec-div 2>&1 | FileCheck --check-prefix=RECIP6 %s
+// RECIP6: "-target-feature" "+recip-vec-div"
+
+// RUN: %clang -target i386-unknown-unknown -### -S %s -mrecip=sqrt 2>&1 | FileCheck --check-prefix=RECIP7 %s
+// RECIP7: "-target-feature" "+recip-sqrt"
+
+// RUN: %clang -target i386-unknown-unknown -### -S %s -mrecip=vec-sqrt 2>&1 | FileCheck --check-prefix=RECIP8 %s
+// RECIP8: "-target-feature" "+recip-vec-sqrt"
+
+// RUN: %clang -target i386-unknown-unknown -### -S %s -mrecip=div,vec-div 2>&1 | FileCheck --check-prefix=RECIP9 %s
+// RECIP9: "-target-feature" "+recip-div" "-target-feature" "+recip-vec-div"
+
+// RUN: %clang -target i386-unknown-unknown -### -S %s -mrecip=div,sqrt 2>&1 | FileCheck --check-prefix=RECIP10 %s
+// RECIP10: "-target-feature" "+recip-div" "-target-feature" "+recip-sqrt"
+
+// RUN: %clang -target i386-unknown-unknown -### -S %s -mrecip=div,!vec-sqrt 2>&1 | FileCheck --check-prefix=RECIP11 %s
+// RECIP11: "-target-feature" "+recip-div" "-target-feature" "-recip-vec-sqrt"
+
+// RUN: %clang -target i386-unknown-unknown -### -S %s -mrecip=bogus 2>&1 | FileCheck --check-prefix=RECIP12 %s
+// RECIP12: error: unsupported argument
+
+// RUN: %clang -target i386-unknown-unknown -### -S %s -mrecip=div,div,div,div,div 2>&1 | FileCheck --check-prefix=RECIP13 %s
+// RECIP13: error: invalid argument
+
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