Merge "Fix ARM hardfloat detection in linux"
diff --git a/src/platform-linux.cc b/src/platform-linux.cc
index 9781407..6c4a549 100644
--- a/src/platform-linux.cc
+++ b/src/platform-linux.cc
@@ -190,48 +190,43 @@
}
-// Simple helper function to detect whether the C code is compiled with
-// option -mfloat-abi=hard. The register d0 is loaded with 1.0 and the register
-// pair r0, r1 is loaded with 0.0. If -mfloat-abi=hard is pased to GCC then
-// calling this will return 1.0 and otherwise 0.0.
-static void ArmUsingHardFloatHelper() {
- asm("mov r0, #0":::"r0");
-#if defined(__VFP_FP__) && !defined(__SOFTFP__)
- // Load 0x3ff00000 into r1 using instructions available in both ARM
- // and Thumb mode.
- asm("mov r1, #3":::"r1");
- asm("mov r2, #255":::"r2");
- asm("lsl r1, r1, #8":::"r1");
- asm("orr r1, r1, r2":::"r1");
- asm("lsl r1, r1, #20":::"r1");
- // For vmov d0, r0, r1 use ARM mode.
-#ifdef __thumb__
- asm volatile(
- "@ Enter ARM Mode \n\t"
- " adr r3, 1f \n\t"
- " bx r3 \n\t"
- " .ALIGN 4 \n\t"
- " .ARM \n"
- "1: vmov d0, r0, r1 \n\t"
- "@ Enter THUMB Mode\n\t"
- " adr r3, 2f+1 \n\t"
- " bx r3 \n\t"
- " .THUMB \n"
- "2: \n\t":::"r3");
-#else
- asm("vmov d0, r0, r1");
-#endif // __thumb__
-#endif // defined(__VFP_FP__) && !defined(__SOFTFP__)
- asm("mov r1, #0":::"r1");
-}
-
-
bool OS::ArmUsingHardFloat() {
- // Cast helper function from returning void to returning double.
- typedef double (*F)();
- F f = FUNCTION_CAST<F>(FUNCTION_ADDR(ArmUsingHardFloatHelper));
- return f() == 1.0;
+ // GCC versions 4.6 and above define __ARM_PCS or __ARM_PCS_VFP to specify
+ // the Floating Point ABI used (PCS stands for Procedure Call Standard).
+ // We use these as well as a couple of other defines to statically determine
+ // what FP ABI used.
+ // GCC versions 4.4 and below don't support hard-fp.
+ // GCC versions 4.5 may support hard-fp without defining __ARM_PCS or
+ // __ARM_PCS_VFP.
+
+#define GCC_VERSION (__GNUC__ * 10000 \
+ + __GNUC_MINOR__ * 100 \
+ + __GNUC_PATCHLEVEL__)
+#if GCC_VERSION >= 40600
+#if defined(__ARM_PCS_VFP)
+ return true;
+#else
+ return false;
+#endif
+
+#elif GCC_VERSION < 40500
+ return false;
+
+#else
+#if defined(__ARM_PCS_VFP)
+ return true;
+#elif defined(__ARM_PCS) || defined(__SOFTFP) || !defined(__VFP_FP__)
+ return false;
+#else
+#error "Your version of GCC does not report the FP ABI compiled for." \
+ "Please report it on this issue" \
+ "http://code.google.com/p/v8/issues/detail?id=2140"
+
+#endif
+#endif
+#undef GCC_VERSION
}
+
#endif // def __arm__