Reviewers: Jakob,
Description:
MIPS: port ARM: Changed the handling of compiletime CPU feature detection
Another port of an older arm commit, which was not upstreamed at the time.
Ported r7754 (ef678641)
BUG=
TEST=
Please review this at http://codereview.chromium.org/7809016/
Affected files:
M src/mips/assembler-mips.cc
M src/platform-linux.cc
Index: src/mips/assembler-mips.cc
diff --git a/src/mips/assembler-mips.cc b/src/mips/assembler-mips.cc
index
28ac5577605146d0d3bf127523987b81dbac0c3a..f30f38bb7581877fe97d053ead59e6b517094f3a
100644
--- a/src/mips/assembler-mips.cc
+++ b/src/mips/assembler-mips.cc
@@ -49,11 +49,47 @@ bool CpuFeatures::initialized_ = false;
unsigned CpuFeatures::supported_ = 0;
unsigned CpuFeatures::found_by_runtime_probing_ = 0;
+
+// Get the CPU features enabled by the build. For cross compilation the
+// preprocessor symbols CAN_USE_FPU_INSTRUCTIONS
+// can be defined to enable FPU instructions when building the
+// snapshot.
+static uint64_t CpuFeaturesImpliedByCompiler() {
+ uint64_t answer = 0;
+#ifdef CAN_USE_FPU_INSTRUCTIONS
+ answer |= 1u << FPU;
+#endif // def CAN_USE_FPU_INSTRUCTIONS
+
+#ifdef __mips__
+ // If the compiler is allowed to use FPU then we can use FPU too in our
code
+ // generation even when generating snapshots. This won't work for cross
+ // compilation.
+#if(defined(__mips_hard_float) && __mips_hard_float != 0)
+ answer |= 1u << FPU;
+#endif // defined(__mips_hard_float) && __mips_hard_float != 0
+#endif // def __mips__
+
+ return answer;
+}
+
+
void CpuFeatures::Probe() {
ASSERT(!initialized_);
#ifdef DEBUG
initialized_ = true;
#endif
+
+ // Get the features implied by the OS and the compiler settings. This is
the
+ // minimal set of features which is also allowed for generated code in
the
+ // snapshot.
+ supported_ |= OS::CpuFeaturesImpliedByPlatform();
+ supported_ |= CpuFeaturesImpliedByCompiler();
+
+ if (Serializer::enabled()) {
+ // No probing for features if we might serialize (generate snapshot).
+ return;
+ }
+
// If the compiler is allowed to use fpu then we can use fpu too in our
// code generation.
#if !defined(__mips__)
@@ -62,11 +98,7 @@ void CpuFeatures::Probe() {
supported_ |= 1u << FPU;
}
#else
- if (Serializer::enabled()) {
- supported_ |= OS::CpuFeaturesImpliedByPlatform();
- return; // No features if we might serialize.
- }
-
+ // Probe for additional features not already known to be available.
if (OS::MipsCpuHasFeature(FPU)) {
// This implementation also sets the FPU flags if
// runtime detection of FPU returns true.
Index: src/platform-linux.cc
diff --git a/src/platform-linux.cc b/src/platform-linux.cc
index
362bf47cc1c5b5309e73dc3845f1237eba5ee2b3..b152dae9a61ec7ecbf4dd7762cbd6c236ba82c58
100644
--- a/src/platform-linux.cc
+++ b/src/platform-linux.cc
@@ -130,13 +130,7 @@ void OS::Setup() {
uint64_t OS::CpuFeaturesImpliedByPlatform() {
-#if(defined(__mips_hard_float) && __mips_hard_float != 0)
- // Here gcc is telling us that we are on an MIPS and gcc is assuming
that we
- // have FPU instructions. If gcc can assume it then so can we.
- return 1u << FPU;
-#else
return 0; // Linux runs on anything.
-#endif
}
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