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c/7594: 3.1.1, 3.2 branch ICE on legal code
- From: Richard Zidlicky <rz at linux-m68k dot org>
- To: gcc-gnats at gcc dot gnu dot org
- Date: Wed, 14 Aug 2002 12:55:25 +0200
- Subject: c/7594: 3.1.1, 3.2 branch ICE on legal code
>Number: 7594
>Category: c
>Synopsis: ICE on legal code
>Confidential: no
>Severity: serious
>Priority: medium
>Responsible: unassigned
>State: open
>Class: ice-on-legal-code
>Submitter-Id: net
>Arrival-Date: Wed Aug 14 04:36:01 PDT 2002
>Closed-Date:
>Last-Modified:
>Originator: Richard Zidlicky
>Release: 3.2 20020806 (prerelease) and 3.1.1
>Organization:
>Environment:
native and crosscompiled
configured with: ../gcc-3.2-cvs/configure --enable-languages=c --disable-checking --with-newlib --without-headers --target=m68k-linux : (reconfigured) ../gcc-3.2-cvs/configure --enable-languages=c --disable-checking --with-newlib --without-headers --target=m68k-linux
>Description:
following testcase triggers ICE:
#### compile with -O0 to trigger ICE ####
extern void (**table)(void);
typedef unsigned short uw16;
typedef unsigned short uw16;
typedef unsigned int gshort;
register uw16 *pc asm("%a4");
register gshort code asm("%d6");
void QMExecuteLoop(uw16 *oldPC)
{
table[code=(*(uw16*)(pc++))]();
}
########################################
Problem is caused by gen_lowpart() returning a REG instead of an
SUBREG expression in certain cases. This is caused by some code
in simplify_subreg around lines 2644 in simplify-rtx.c
>How-To-Repeat:
>Fix:
Workaround for m68k-linux is to disable the code responsible
for this simplification:
--- gcc-3.2-cvs/gcc/simplify-rtx.c.rz Wed Mar 6 23:43:21 2002
+++ gcc-3.2-cvs/gcc/simplify-rtx.c Wed Aug 14 13:09:30 2002
@@ -2618,6 +2618,7 @@
suppress this simplification. If the hard register is the stack,
frame, or argument pointer, leave this as a SUBREG. */
+#if 0
if (REG_P (op)
&& (! REG_FUNCTION_VALUE_P (op)
|| ! rtx_equal_function_value_matters)
@@ -2662,6 +2663,7 @@
return x;
}
}
+#endif
/* If we have a SUBREG of a register that we are replacing and we are
replacing it with a MEM, make a new MEM and try replacing the
>Release-Note:
>Audit-Trail:
>Unformatted: