Bug 99456
| Summary: | |||
|---|---|---|---|
| Product: | [Retired] Red Hat Raw Hide | Reporter: | hjl |
| Component: | gcc | Assignee: | Vladimir Makarov <vmakarov> |
| Status: | CLOSED NOTABUG | QA Contact: | |
| Severity: | low | Docs Contact: | |
| Priority: | low | ||
| Version: | 1.0 | CC: | tao |
| Target Milestone: | --- | ||
| Target Release: | --- | ||
| Hardware: | ia64 | ||
| OS: | Linux | ||
| Whiteboard: | |||
| Fixed In Version: | Doc Type: | Bug Fix | |
| Doc Text: | Story Points: | --- | |
| Clone Of: | Environment: | ||
| Last Closed: | 2003-07-23 17:15:16 UTC | Type: | --- |
| Regression: | --- | Mount Type: | --- |
| Documentation: | --- | CRM: | |
| Verified Versions: | Category: | --- | |
| oVirt Team: | --- | RHEL 7.3 requirements from Atomic Host: | |
| Cloudforms Team: | --- | Target Upstream Version: | |
| Embargoed: | |||
ISSUE TRACKER 26067 opened as sev 3 It is not a bug (at least with user's point of view). The code generated for -O1 is the same as for -02 (lprefetch is not predicated). HJ found that prefetch is predicated in RTL (when -O1) but the corresponding lprefetch insn is not predicated in assembler code therefore he reported about this. I think we should not make a patch (or use already created patch) for gcc especially on this stage. More information could be found in http://gcc.gnu.org/ml/gcc/2003-07/msg01655.html http://gcc.gnu.org/ml/gcc/2003-07/msg01657.html |
[hjl@gnu-3 predicate]$ cat bar.i void prefetch (void *p, int s) { if (s) __builtin_prefetch (p, 1, 1); } [hjl@gnu-3 predicate]$ gcc -Wall -O bar.i -S [hjl@gnu-3 predicate]$ cat bar.s .pred.safe_across_calls p1-p5,p16-p63 .text .align 16 .global prefetch# .proc prefetch# prefetch: .prologue .body cmp4.eq p6, p7 = 0, r33 ;; lfetch.excl.nt1 [r32] br.ret.sptk.many rp ;; .endp prefetch# The problem is there is no (p7) before "lfetch.excl.nt1 [r32]". That means __builtin_prefetch (p, 1, 1); is always executed even if 's' is 0.