We found that
std::basic_string<char, std::char_traits<char>, std::allocator<char>
::copy(char*, unsigned long, unsigned long) const
got miscompiled for ARC because reorg thought that all call-clobbered
registers were dead after a conditional call.
I can't reproduce the test case with current trunk + ARC port, but I reckon
this is just due to the fickleness of the register allocator. Chances are,
every other version, some other obscure function is miscompiled without
this patch.
bootstrapped on i686-pc-linux-gnu.
OK to apply?
2013-04-29 Claudiu Zissulescu <claz...@synopsys.com>
* resource.c (mark_target_live_regs): Compute resources taking
into account if a call is predicated or not.
diff --git a/gcc/resource.c b/gcc/resource.c
Index: resource.c
===================================================================
--- resource.c (revision 202295)
+++ resource.c (working copy)
@@ -994,11 +994,18 @@ mark_target_live_regs (rtx insns, rtx ta
if (CALL_P (real_insn))
{
- /* CALL clobbers all call-used regs that aren't fixed except
- sp, ap, and fp. Do this before setting the result of the
- call live. */
- AND_COMPL_HARD_REG_SET (current_live_regs,
- regs_invalidated_by_call);
+ /* Values in call-clobbered registers survive a COND_EXEC CALL
+ if that is not executed; this matters for resoure use because
+ they may be used by a complementarily (or more strictly)
+ predicated instruction, or if the CALL is NORETURN. */
+ if (GET_CODE (PATTERN (real_insn)) != COND_EXEC)
+ {
+ /* CALL clobbers all call-used regs that aren't fixed except
+ sp, ap, and fp. Do this before setting the result of the
+ call live. */
+ AND_COMPL_HARD_REG_SET (current_live_regs,
+ regs_invalidated_by_call);
+ }
/* A CALL_INSN sets any global register live, since it may
have been modified by the call. */
