[XRay][SystemZ] Use stckf for non-clang compilers #125289
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Turns out there are users who use gcc to compile compiler-rt. Using the clang-specific builtin function `__builtin_readcyclecounter()` does not work in this case. Solution is to use inline assembly using the stckf instruction in case the compiler is not clang.
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@llvm/pr-subscribers-xray Author: Kai Nacke (redstar) ChangesTurns out there are users who use gcc to compile compiler-rt. Using the clang-specific builtin function Full diff: https://github.com/llvm/llvm-project/pull/125289.diff 1 Files Affected:
diff --git a/compiler-rt/lib/xray/xray_tsc.h b/compiler-rt/lib/xray/xray_tsc.h
index 17e06c7035d85c..06f509cd1b09b9 100644
--- a/compiler-rt/lib/xray/xray_tsc.h
+++ b/compiler-rt/lib/xray/xray_tsc.h
@@ -96,7 +96,13 @@ namespace __xray {
inline bool probeRequiredCPUFeatures() XRAY_NEVER_INSTRUMENT { return true; }
ALWAYS_INLINE uint64_t readTSC(uint8_t &CPU) XRAY_NEVER_INSTRUMENT {
+#if defined(__clang__)
return __builtin_readcyclecounter();
+#else
+ uint64_t Cycles;
+ asm volatile("stckf %0" : /* No output. */ : "Q"(Cycles) : "cc");
+ return Cycles;
+#endif
}
inline uint64_t getTSCFrequency() XRAY_NEVER_INSTRUMENT {
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MaskRay
approved these changes
Feb 1, 2025
compiler-rt/lib/xray/xray_tsc.h
Outdated
| @@ -96,7 +96,13 @@ namespace __xray { | |||
| inline bool probeRequiredCPUFeatures() XRAY_NEVER_INSTRUMENT { return true; } | |||
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| ALWAYS_INLINE uint64_t readTSC(uint8_t &CPU) XRAY_NEVER_INSTRUMENT { | |||
| #if defined(__clang__) | |||
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__has_builtin(__builtin_readcyclecounter) ?
compiler-rt/lib/xray/xray_tsc.h
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| return __builtin_readcyclecounter(); | ||
| #else | ||
| uint64_t Cycles; | ||
| asm volatile("stckf %0" : /* No output. */ : "Q"(Cycles) : "cc"); |
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remove the unnecessary comment /* No output. */. In the majority of places we assume that the user is aware of the : : syntax
Icohedron
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Feb 11, 2025
Turns out there are users who use gcc to compile compiler-rt. Using the clang-specific builtin function `__builtin_readcyclecounter()` does not work in this case. Solution is to use inline assembly using the stckf instruction in case the compiler is not clang.
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Turns out there are users who use gcc to compile compiler-rt. Using the clang-specific builtin function
__builtin_readcyclecounter()does not work in this case.Solution is to use inline assembly using the stckf instruction in case the compiler is not clang.