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Re: optimization/6233: simple loop miscompilation
On Tue, Apr 09, 2002 at 05:41:07PM -0700, Richard Henderson wrote:
> On Wed, Apr 10, 2002 at 09:30:14AM +0930, Alan Modra wrote:
> > Sledgehammer to crack a nut? Should I instead specifically search
> > for the use_mem_scratch?
>
> Please.
OK. i686-linux native bootstrap and reg test in progress.
* rtlanal.c (pure_call_p): New function.
* rtl.h (pure_call_p): Declare.
* loop.c (prescan_loop): Use it to set has_nonconst_call.
Index: gcc/loop.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/loop.c,v
retrieving revision 1.394
diff -u -p -r1.394 loop.c
--- gcc/loop.c 3 Apr 2002 07:56:44 -0000 1.394
+++ gcc/loop.c 10 Apr 2002 00:56:54 -0000
@@ -2493,6 +2493,8 @@ prescan_loop (loop)
loop_info->unknown_address_altered = 1;
loop_info->has_nonconst_call = 1;
}
+ else if (pure_call_p (insn))
+ loop_info->has_nonconst_call = 1;
loop_info->has_call = 1;
if (can_throw_internal (insn))
loop_info->has_multiple_exit_targets = 1;
Index: gcc/rtl.h
===================================================================
RCS file: /cvs/gcc/gcc/gcc/rtl.h,v
retrieving revision 1.337
diff -u -p -r1.337 rtl.h
--- gcc/rtl.h 1 Apr 2002 03:18:49 -0000 1.337
+++ gcc/rtl.h 10 Apr 2002 00:56:56 -0000
@@ -1502,6 +1502,7 @@ extern rtx find_reg_equal_equiv_note PAR
extern int find_reg_fusage PARAMS ((rtx, enum rtx_code, rtx));
extern int find_regno_fusage PARAMS ((rtx, enum rtx_code,
unsigned int));
+extern int pure_call_p PARAMS ((rtx));
extern void remove_note PARAMS ((rtx, rtx));
extern int side_effects_p PARAMS ((rtx));
extern int volatile_refs_p PARAMS ((rtx));
Index: gcc/rtlanal.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/rtlanal.c,v
retrieving revision 1.130
diff -u -p -r1.130 rtlanal.c
--- gcc/rtlanal.c 28 Mar 2002 12:25:18 -0000 1.130
+++ gcc/rtlanal.c 10 Apr 2002 00:56:58 -0000
@@ -2011,6 +2011,31 @@ find_regno_fusage (insn, code, regno)
return 0;
}
+
+/* Return true if INSN is a call to a pure function. */
+
+int
+pure_call_p (insn)
+ rtx insn;
+{
+ rtx link;
+
+ if (GET_CODE (insn) != CALL_INSN || ! CONST_OR_PURE_CALL_P (insn))
+ return 0;
+
+ /* Look for the note that differentiates const and pure functions. */
+ for (link = CALL_INSN_FUNCTION_USAGE (insn); link; link = XEXP (link, 1))
+ {
+ rtx u, m;
+
+ if (GET_CODE (u = XEXP (link, 0)) == USE
+ && GET_CODE (m = XEXP (u, 0)) == MEM && GET_MODE (m) == BLKmode
+ && GET_CODE (XEXP (m, 0)) == SCRATCH)
+ return 1;
+ }
+
+ return 0;
+}
/* Remove register note NOTE from the REG_NOTES of INSN. */
--
Alan Modra
IBM OzLabs - Linux Technology Centre