Reviewers: alph, Benedikt Meurer,
Message:
Here is the assembler code for the function without and with volatile:
=> 0x085647e0 <+0>: sub $0x2c,%esp
0x085647e3 <+3>: lea 0x18(%esp),%eax
0x085647e7 <+7>: movl $0x0,0x4(%esp)
0x085647ef <+15>: mov %eax,(%esp)
0x085647f2 <+18>: call 0x804a0d0 <gettimeofday@plt>
0x085647f7 <+23>: test %eax,%eax
0x085647f9 <+25>: js 0x8564818
<_ZN2v88internal2OS17TimeCurrentMillisEv+56>
0x085647fb <+27>: fildl 0x18(%esp)
0x085647ff <+31>: flds 0x8ebb0d4
0x08564805 <+37>: fmul %st,%st(1)
0x08564807 <+39>: fildl 0x1c(%esp)
0x0856480b <+43>: add $0x2c,%esp
0x0856480e <+46>: fdivp %st,%st(1)
0x08564810 <+48>: faddp %st,%st(1)
0x08564812 <+50>: ret
0x08564813 <+51>: nop
0x08564814 <+52>: lea 0x0(%esi,%eiz,1),%esi
0x08564818 <+56>: fldz
0x0856481a <+58>: add $0x2c,%esp
0x0856481d <+61>: ret
=> 0x085647e0 <+0>: sub $0x2c,%esp
0x085647e3 <+3>: lea 0x18(%esp),%eax
0x085647e7 <+7>: movl $0x0,0x4(%esp)
0x085647ef <+15>: mov %eax,(%esp)
0x085647f2 <+18>: call 0x804a0d0 <gettimeofday@plt>
0x085647f7 <+23>: test %eax,%eax
0x085647f9 <+25>: js 0x8564820
<_ZN2v88internal2OS17TimeCurrentMillisEv+64>
0x085647fb <+27>: fildl 0x18(%esp)
0x085647ff <+31>: flds 0x8ebb0d4
0x08564805 <+37>: fmul %st,%st(1)
0x08564807 <+39>: fildl 0x1c(%esp)
0x0856480b <+43>: fdivp %st,%st(1)
0x0856480d <+45>: faddp %st,%st(1)
0x0856480f <+47>: fstpl 0x10(%esp)
0x08564813 <+51>: fldl 0x10(%esp)
0x08564817 <+55>: add $0x2c,%esp
0x0856481a <+58>: ret
0x0856481b <+59>: nop
0x0856481c <+60>: lea 0x0(%esi,%eiz,1),%esi
0x08564820 <+64>: fldz
0x08564822 <+66>: add $0x2c,%esp
0x08564825 <+69>: ret
Description:
OS::TimeCurrentMillis should return double not long double
Make sure the value returned from OS::TimeCurrentMillis is cast to double
(not
long double). I also tried assigning the result of the expression to double
variable and doing static_cast<double> but those are not enough on gcc. Not
sure
if we want this patch. I'm going to change profiler code to return
microseconds
as int64_t anyways.
BUG=v8:2824
Please review this at https://codereview.chromium.org/21848004/
SVN Base: https://v8.googlecode.com/svn/branches/bleeding_edge
Affected files:
M src/platform-posix.cc
Index: src/platform-posix.cc
diff --git a/src/platform-posix.cc b/src/platform-posix.cc
index
13b819bd1e79c1452979961fd082c2af73171e56..758e09d7a51bf3618e52fb3ea4856f138afaff58
100644
--- a/src/platform-posix.cc
+++ b/src/platform-posix.cc
@@ -320,8 +320,10 @@ int OS::GetUserTime(uint32_t* secs, uint32_t* usecs) {
double OS::TimeCurrentMillis() {
struct timeval tv;
if (gettimeofday(&tv, NULL) < 0) return 0.0;
- return (static_cast<double>(tv.tv_sec) * 1000) +
- (static_cast<double>(tv.tv_usec) / 1000);
+ volatile double result =
+ (static_cast<double>(tv.tv_sec) * 1000) +
+ (static_cast<double>(tv.tv_usec) / 1000);
+ return result;
}
--
--
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