runtime: fix nanotime for macOS Sierra

This is a cherry-pick of https://go-review.googlesource.com/24812 to the release-branch-go1.4 In the beta version of the macOS Sierra (10.12) release, the gettimeofday system call changed on x86. Previously it always returned the time in the AX/DX registers. Now, if AX is returned as 0, it means that the system call has stored the values into the memory pointed to by the first argument, just as the libc gettimeofday function does. The libc function handles both cases, and we need to do so as well. Fixes golang#16272. Change-Id: I490ed0a82e251fce73becc4722cbe276feebc7b7 Reviewed-on: https://go-review.googlesource.com/31729 Reviewed-by: Brad Fitzpatrick <[email protected]>
wheatman · Jul 18, 2018 · 12aed41 · 12aed41
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commit 12aed41
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diff --git a/src/runtime/sys_darwin_386.s b/src/runtime/sys_darwin_386.s
@@ -187,6 +187,11 @@ systime:
 	MOVL	$0, 8(SP)	// time zone pointer
 	MOVL	$116, AX
 	INT	$0x80
+	CMPL	AX, $0
+	JNE	inreg
+	MOVL	12(SP), AX
+	MOVL	16(SP), DX
+inreg:
 	// sec is in AX, usec in DX
 	// convert to DX:AX nsec
 	MOVL	DX, BX

diff --git a/src/runtime/sys_darwin_amd64.s b/src/runtime/sys_darwin_amd64.s
@@ -141,10 +141,15 @@ timeloop:
 
 systime:
 	// Fall back to system call (usually first call in this thread).
-	MOVQ	SP, DI	// must be non-nil, unused
+	MOVQ	SP, DI
 	MOVQ	$0, SI
 	MOVL	$(0x2000000+116), AX
 	SYSCALL
+	CMPQ	AX, $0
+	JNE	inreg
+	MOVQ	0(SP), AX
+	MOVL	8(SP), DX
+inreg:
 	// sec is in AX, usec in DX
 	// return nsec in AX
 	IMULQ	$1000000000, AX