ref: a7f13757d67c3169a938c95d2db667d1bd4ee407
parent: bbdcad5c85ca1a0daa21bf1f8f70ea9394cb7a02
author: Sigrid Solveig Haflínudóttir <[email protected]>
date: Sun Nov 1 09:26:11 EST 2020
clean up assembly mess
--- a/b.c
+++ b/b.c
@@ -19,11 +19,8 @@
Res cpuid(ulong ax, ulong cx);
-void _tstart(uvlong *c);
void _tend(uvlong *c);
-void _tstartp(uvlong *c);
void _tendp(uvlong *c);
-void (*tstart)(uvlong *c);
void (*tend)(uvlong *c);
uvlong
@@ -66,15 +63,9 @@
fmtinstall(L'σ', σfmt);
fmtinstall(L'τ', τfmt);
- if(tstart == nil){+ if(tend == nil){r = cpuid(0x80000001, 2);
- if((r.dx & (1<<27)) != 0){- tstart = _tstartp;
- tend = _tendp;
- }else{- tstart = _tstart;
- tend = _tend;
- }
+ tend = (r.dx & (1<<27)) != 0 ? _tendp : _tend;
}
memset(b, 0, sizeof(*b));
@@ -87,8 +78,8 @@
uvlong v;
for(i = 0, v = 0; i < 100; i++){uvlong s, e;
- _tstart(&s);
- _tend(&e);
+ tstart(&s);
+ tend(&e);
v += e - s;
}
adj = v / i;
--- a/b.h
+++ b/b.h
@@ -24,7 +24,7 @@
/* private */
void benchstep(B *b);
-extern void (*tstart)(uvlong *c);
+void tstart(uvlong *c);
extern void (*tend)(uvlong *c);
/* public */
--- a/b_amd64.s
+++ b/b_amd64.s
@@ -1,4 +1,6 @@
-TEXT _tstart(SB), 1, $0
+#define RDTSCP WORD $0x010f; BYTE $0xf9
+
+TEXT tstart(SB), 1, $0
CPUID
RDTSC
MOVL AX, 0(RARG)
@@ -6,21 +8,15 @@
RET
TEXT _tend(SB), 1, $0
- CPUID
+ /* it needs MOVL CR0, AX; MOV AX, CR0 but it's userspace */
RDTSC
MOVL AX, 0(RARG)
MOVL DX, 4(RARG)
- RET
-
-TEXT _tstartp(SB), 1, $0
CPUID
- WORD $0x010f; BYTE $0xf9 // RDTSCP
- MOVL AX, 0(RARG)
- MOVL DX, 4(RARG)
RET
TEXT _tendp(SB), 1, $0
- WORD $0x010f; BYTE $0xf9 // RDTSCP
+ RDTSCP
MOVL AX, 0(RARG)
MOVL DX, 4(RARG)
CPUID