Hi chandlerc, echristo, rafael, grosbach,
Some versions of Sandybridge, Ivybridge, Haswell, and Broadwell CPUs don't
support AVX. Currently, getHostCPUName changes the CPU name to Nehalem when it
detects one of the CPUs. This also ends up disabling other features that these
CPUs might still have as well as changing the scheduling model, etc.
This patch attempts to correct this by allowing the CPU name to work unaltered
and then use getHostCPUFeatures to explicitly specify which features are
enabled and disabled.
Similar patch will also be made to llc.
http://reviews.llvm.org/D8694
Files:
lib/Driver/Tools.cpp
Index: lib/Driver/Tools.cpp
===================================================================
--- lib/Driver/Tools.cpp
+++ lib/Driver/Tools.cpp
@@ -1566,6 +1566,17 @@
static void getX86TargetFeatures(const Driver &D, const llvm::Triple &Triple,
const ArgList &Args,
std::vector<const char *> &Features) {
+ // If -march=native, autodetect the feature list.
+ if (const Arg *A = Args.getLastArg(options::OPT_march_EQ)) {
+ if (StringRef(A->getValue()) == "native") {
+ llvm::StringMap<bool> HostFeatures;
+ if (llvm::sys::getHostCPUFeatures(HostFeatures))
+ for (auto &F : HostFeatures)
+ Features.push_back(Args.MakeArgString((F.second ? "+" : "-") +
+ F.first()));
+ }
+ }
+
if (Triple.getArchName() == "x86_64h") {
// x86_64h implies quite a few of the more modern subtarget features
// for Haswell class CPUs, but not all of them. Opt-out of a few.
EMAIL PREFERENCES
http://reviews.llvm.org/settings/panel/emailpreferences/
Index: lib/Driver/Tools.cpp
===================================================================
--- lib/Driver/Tools.cpp
+++ lib/Driver/Tools.cpp
@@ -1566,6 +1566,17 @@
static void getX86TargetFeatures(const Driver &D, const llvm::Triple &Triple,
const ArgList &Args,
std::vector<const char *> &Features) {
+ // If -march=native, autodetect the feature list.
+ if (const Arg *A = Args.getLastArg(options::OPT_march_EQ)) {
+ if (StringRef(A->getValue()) == "native") {
+ llvm::StringMap<bool> HostFeatures;
+ if (llvm::sys::getHostCPUFeatures(HostFeatures))
+ for (auto &F : HostFeatures)
+ Features.push_back(Args.MakeArgString((F.second ? "+" : "-") +
+ F.first()));
+ }
+ }
+
if (Triple.getArchName() == "x86_64h") {
// x86_64h implies quite a few of the more modern subtarget features
// for Haswell class CPUs, but not all of them. Opt-out of a few.
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