Date: Tue, 4 Jun 2002 10:58:37 -0700 From: "David O'Brien" <obrien@FreeBSD.ORG> To: Tor.Egge@cvsup.no.freebsd.org Cc: bde@zeta.org.au, current@FreeBSD.ORG Subject: Re: memset() broken in gcc-3.1 on i386's Message-ID: <20020604105837.A93000@dragon.nuxi.com> In-Reply-To: <20020604030221G.tegge@cvsup.no.freebsd.org>; from Tor.Egge@cvsup.no.freebsd.org on Tue, Jun 04, 2002 at 03:02:21AM %2B0000 References: <20020604084202.Q939-100000@gamplex.bde.org> <20020604110707.H1982-100000@gamplex.bde.org> <20020604030221G.tegge@cvsup.no.freebsd.org>
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On Tue, Jun 04, 2002 at 03:02:21AM +0000, Tor.Egge@cvsup.no.freebsd.org wrote:
> > Actually, it broke fsck_ffs.
> >
> > Workaround to avoid the known broken case:
>
> The brokenness in ix86_expand_clrstr is quite visible when you
> compare the function with ix86_expand_movstr.
Fixed in rev 1.368.2.10. "* i386.c (expand_movstr, expand_clrstr): Fix
inline-all-stringops sequence."
But their fix is a little different from yours:
Index: i386.c
===================================================================
RCS file: /cvs/gcc/egcs/gcc/config/i386/i386.c,v
retrieving revision 1.368.2.9
retrieving revision 1.368.2.10
diff -u -r1.368.2.9 -r1.368.2.10
--- i386.c 23 Apr 2002 08:11:22 -0000 1.368.2.9
+++ i386.c 22 May 2002 12:23:53 -0000 1.368.2.10
@@ -7959,6 +7959,10 @@
&& GET_CODE (ix86_compare_op1) == CONST_INT
&& mode != HImode
&& (unsigned int) INTVAL (ix86_compare_op1) != 0xffffffff
+ /* The operand still must be representable as sign extended value. */
+ && (!TARGET_64BIT
+ || GET_MODE (ix86_compare_op0) != DImode
+ || (unsigned int) INTVAL (ix86_compare_op1) != 0x7fffffff)
&& GET_CODE (operands[2]) == CONST_INT
&& GET_CODE (operands[3]) == CONST_INT)
{
@@ -9130,6 +9134,9 @@
{
rtx countreg2;
rtx label = NULL;
+ int desired_alignment = (TARGET_PENTIUMPRO
+ && (count == 0 || count >= (unsigned int) 260)
+ ? 8 : UNITS_PER_WORD);
/* In case we don't know anything about the alignment, default to
library version, since it is usually equally fast and result in
@@ -9159,10 +9166,7 @@
This is quite costy. Maybe we can revisit this decision later or
add some customizability to this code. */
- if (count == 0
- && align < (TARGET_PENTIUMPRO && (count == 0
- || count >= (unsigned int) 260)
- ? 8 : UNITS_PER_WORD))
+ if (count == 0 && align < desired_alignment)
{
label = gen_label_rtx ();
emit_cmp_and_jump_insns (countreg, GEN_INT (UNITS_PER_WORD - 1),
@@ -9184,10 +9188,7 @@
emit_label (label);
LABEL_NUSES (label) = 1;
}
- if (align <= 4
- && ((TARGET_PENTIUMPRO && (count == 0
- || count >= (unsigned int) 260))
- || TARGET_64BIT))
+ if (align <= 4 && desired_alignment > 4)
{
rtx label = ix86_expand_aligntest (destreg, 4);
emit_insn (gen_strmovsi (destreg, srcreg));
@@ -9196,6 +9197,12 @@
LABEL_NUSES (label) = 1;
}
+ if (label && desired_alignment > 4 && !TARGET_64BIT)
+ {
+ emit_label (label);
+ LABEL_NUSES (label) = 1;
+ label = NULL_RTX;
+ }
if (!TARGET_SINGLE_STRINGOP)
emit_insn (gen_cld ());
if (TARGET_64BIT)
@@ -9341,6 +9348,10 @@
{
rtx countreg2;
rtx label = NULL;
+ /* Compute desired alignment of the string operation. */
+ int desired_alignment = (TARGET_PENTIUMPRO
+ && (count == 0 || count >= (unsigned int) 260)
+ ? 8 : UNITS_PER_WORD);
/* In case we don't know anything about the alignment, default to
library version, since it is usually equally fast and result in
@@ -9355,13 +9366,10 @@
countreg = copy_to_mode_reg (counter_mode, count_exp);
zeroreg = copy_to_mode_reg (Pmode, const0_rtx);
- if (count == 0
- && align < (TARGET_PENTIUMPRO && (count == 0
- || count >= (unsigned int) 260)
- ? 8 : UNITS_PER_WORD))
+ if (count == 0 && align < desired_alignment)
{
label = gen_label_rtx ();
- emit_cmp_and_jump_insns (countreg, GEN_INT (UNITS_PER_WORD - 1),
+ emit_cmp_and_jump_insns (countreg, GEN_INT (desired_alignment - 1),
LEU, 0, counter_mode, 1, label);
}
if (align <= 1)
@@ -9382,8 +9390,7 @@
emit_label (label);
LABEL_NUSES (label) = 1;
}
- if (align <= 4 && TARGET_PENTIUMPRO && (count == 0
- || count >= (unsigned int) 260))
+ if (align <= 4 && desired_alignment > 4)
{
rtx label = ix86_expand_aligntest (destreg, 4);
emit_insn (gen_strsetsi (destreg, (TARGET_64BIT
@@ -9394,6 +9401,13 @@
LABEL_NUSES (label) = 1;
}
+ if (label && desired_alignment > 4 && !TARGET_64BIT)
+ {
+ emit_label (label);
+ LABEL_NUSES (label) = 1;
+ label = NULL_RTX;
+ }
+
if (!TARGET_SINGLE_STRINGOP)
emit_insn (gen_cld ());
if (TARGET_64BIT)
@@ -9409,18 +9423,18 @@
emit_insn (gen_rep_stossi (destreg, countreg2, zeroreg,
destreg, countreg2));
}
-
if (label)
{
emit_label (label);
LABEL_NUSES (label) = 1;
}
+
if (TARGET_64BIT && align > 4 && count != 0 && (count & 4))
emit_insn (gen_strsetsi (destreg,
gen_rtx_SUBREG (SImode, zeroreg, 0)));
if (TARGET_64BIT && (align <= 4 || count == 0))
{
- rtx label = ix86_expand_aligntest (destreg, 2);
+ rtx label = ix86_expand_aligntest (countreg, 2);
emit_insn (gen_strsetsi (destreg,
gen_rtx_SUBREG (SImode, zeroreg, 0)));
emit_label (label);
@@ -9431,7 +9445,7 @@
gen_rtx_SUBREG (HImode, zeroreg, 0)));
if (align <= 2 || count == 0)
{
- rtx label = ix86_expand_aligntest (destreg, 2);
+ rtx label = ix86_expand_aligntest (countreg, 2);
emit_insn (gen_strsethi (destreg,
gen_rtx_SUBREG (HImode, zeroreg, 0)));
emit_label (label);
@@ -9442,7 +9456,7 @@
gen_rtx_SUBREG (QImode, zeroreg, 0)));
if (align <= 1 || count == 0)
{
- rtx label = ix86_expand_aligntest (destreg, 1);
+ rtx label = ix86_expand_aligntest (countreg, 1);
emit_insn (gen_strsetqi (destreg,
gen_rtx_SUBREG (QImode, zeroreg, 0)));
emit_label (label);
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