base/dispatch-x86ish.S (dispatch_x86ish_cpuid): Skip `EFLAGS_ID' dance on AMD64.

[catacomb] / base / dispatch-x86ish.S

diff --git a/base/dispatch-x86ish.S b/base/dispatch-x86ish.S
index 57d8d32..3a14c39 100644 (file)
--- a/base/dispatch-x86ish.S
+++ b/base/dispatch-x86ish.S
@@ -67,7 +67,9 @@ FUNC(dispatch_x86ish_cpuid)
   endprologue
 
        // First, check that this is even a thing, using the complicated
-       // dance with the flags register.
+       // dance with the flags register.  This is unnecessary on AMD64,
+       // which postdates the introduction of `cpuid'.
+#if CPUFAM_X86
        pushf
        pop     DX                      // current flags in d
 
@@ -86,6 +88,7 @@ FUNC(dispatch_x86ish_cpuid)
        pop     DX
        test    edx, EFLAGS_ID
        jnz     8f
+#endif
 
        // OK, that seemed to work.
        cpuid
@@ -108,6 +111,7 @@ FUNC(dispatch_x86ish_cpuid)
        ret
 
        // Failed.
+#if CPUFAM_X86
 8:     xor     eax, eax
        mov     [OUT + 0], eax
        mov     [OUT + 4], eax
@@ -115,6 +119,7 @@ FUNC(dispatch_x86ish_cpuid)
        mov     [OUT + 12], eax
        mov     eax, -1
        jmp     9b
+#endif
 ENDFUNC
 
 ///--------------------------------------------------------------------------
@@ -155,6 +160,43 @@ FUNC(dispatch_x86ish_xmmregisters_p)
 ENDFUNC
 
 ///--------------------------------------------------------------------------
+/// Checking extended control registers.
+
+FUNC(dispatch_x86ish_xgetbv)
+       // Call with two arguments: a pointer Z_OUT to 8 bytes of output space, and
+       // a 32-bit integer C.  Read the 64-bit value of XCR(C), and store it
+       // at Z_OUT.
+
+#if CPUFAM_X86
+#  define Z_OUT edi
+       pushreg edi
+       mov     edi, [esp + 8]
+       mov     ecx, [esp + 12]
+#endif
+#if CPUFAM_AMD64 && ABI_SYSV
+#  define Z_OUT rdi
+       mov     ecx, esi
+#endif
+#if CPUFAM_AMD64 && ABI_WIN
+#  define Z_OUT r8
+       mov     r8, rcx
+       mov     ecx, edx
+#endif
+  endprologue
+
+       xgetbv
+       mov     [Z_OUT + 0], eax
+       mov     [Z_OUT + 4], edx
+
+#if CPUFAM_X86
+       popreg  edi
+#endif
+       ret
+
+#undef Z_OUT
+ENDFUNC
+
+///--------------------------------------------------------------------------
 /// Checking `rdrand'.
 
 FUNC(dispatch_x86ish_rdrand)