gcc 4.0.0 optimization seems to have a problem. In the f function in following source, buf[i+i] = '\0' stores '\0' to buf[2]. But it should store to buf[4]. % cat t.c extern int printf (__const char *__restrict __format, ...); void f(char *buf) { int i; for (i = 0; i < 2; i++) ; printf("i=%d\n", i); buf[i+i] = '\0'; } int main(int argc, char **argv) { char buf[] = "0123456789"; f(buf); printf("%s\n", buf); return 0; } % gcc -v -O2 t.c Using built-in specs. Target: i686-pc-linux-gnu Configured with: ../gcc-4.0.0/configure --prefix=/home/src/gcc Thread model: posix gcc version 4.0.0 /home/src/gcc/libexec/gcc/i686-pc-linux-gnu/4.0.0/cc1 -quiet -v t.c -quiet -dumpbase t.c -mtune=pentiumpro -auxbase t -O2 -version -o /tmp/ccKF4bLU.s ignoring nonexistent directory "/home/src/gcc/lib/gcc/i686-pc-linux-gnu/4.0.0/../../../../i686-pc-linux-gnu/include" #include "..." search starts here: #include <...> search starts here: /usr/local/include /home/src/gcc/include /home/src/gcc/lib/gcc/i686-pc-linux-gnu/4.0.0/include /usr/include End of search list. GNU C version 4.0.0 (i686-pc-linux-gnu) compiled by GNU C version 4.0.0. GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072 as -V -Qy -o /tmp/ccm6JTQG.o /tmp/ccKF4bLU.s GNU assembler version 2.15 (i386-linux) using BFD version 2.15 /home/src/gcc/libexec/gcc/i686-pc-linux-gnu/4.0.0/collect2 --eh-frame-hdr -m elf_i386 -dynamic-linker /lib/ld-linux.so.2 /usr/lib/crt1.o /usr/lib/crti.o /home/src/gcc/lib/gcc/i686-pc-linux-gnu/4.0.0/crtbegin.o -L/home/src/gcc/lib/gcc/i686-pc-linux-gnu/4.0.0 -L/home/src/gcc/lib/gcc/i686-pc-linux-gnu/4.0.0/../../.. /tmp/ccm6JTQG.o -lgcc --as-needed -lgcc_s --no-as-needed -lc -lgcc --as-needed -lgcc_s --no-as-needed /home/src/gcc/lib/gcc/i686-pc-linux-gnu/4.0.0/crtend.o /usr/lib/crtn.o % ./a.out i=2 01 The binary produces "01". But it should be "0123". If gcc 3.3.5 is used, the binary produces "0123".
This is another expand issue: ;; *((char *) (unsigned int) (i + i) + buf) = 0 (insn 27 25 0 (set (mem:QI (plus:SI (mult:SI (reg/v:SI 60 [ i ]) (const_int 1 [0x1])) (reg/v/f:SI 61 [ buf ])) [0 S1 A8]) (const_int 0 [0x0])) -1 (nil) (nil)) Why is it multiplying by one and not by two. Confirmed.
This is a target bug.
Patch here: <http://gcc.gnu.org/ml/gcc-patches/2005-05/msg00073.html>
Subject: Bug 21297 CVSROOT: /cvs/gcc Module name: gcc Changes by: jakub@gcc.gnu.org 2005-05-03 12:58:13 Modified files: gcc : ChangeLog gcc/config/i386: i386.c gcc/testsuite : ChangeLog Added files: gcc/testsuite/gcc.c-torture/execute: 20050502-2.c Log message: PR target/21297 * config/i386/i386.c (legitimize_address): When canonicalizing ASHIFT into MULT, multiply by 1 << shift_count instead of 1 << log2 (shift_count). * gcc.c-torture/execute/20050502-2.c: New test. Patches: http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/ChangeLog.diff?cvsroot=gcc&r1=2.8572&r2=2.8573 http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/config/i386/i386.c.diff?cvsroot=gcc&r1=1.816&r2=1.817 http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/testsuite/ChangeLog.diff?cvsroot=gcc&r1=1.5433&r2=1.5434 http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/testsuite/gcc.c-torture/execute/20050502-2.c.diff?cvsroot=gcc&r1=NONE&r2=1.1
Subject: Bug 21297 CVSROOT: /cvs/gcc Module name: gcc Branch: gcc-4_0-branch Changes by: jakub@gcc.gnu.org 2005-05-04 07:24:34 Modified files: gcc : ChangeLog gcc/testsuite : ChangeLog gcc/config/i386: i386.c Added files: gcc/testsuite/gcc.c-torture/execute: 20050502-2.c Log message: PR target/21297 * config/i386/i386.c (legitimize_address): When canonicalizing ASHIFT into MULT, multiply by 1 << shift_count instead of 1 << log2 (shift_count). * gcc.c-torture/execute/20050502-2.c: New test. Patches: http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/ChangeLog.diff?cvsroot=gcc&only_with_tag=gcc-4_0-branch&r1=2.7592.2.214&r2=2.7592.2.215 http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/testsuite/ChangeLog.diff?cvsroot=gcc&only_with_tag=gcc-4_0-branch&r1=1.5084.2.157&r2=1.5084.2.158 http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/config/i386/i386.c.diff?cvsroot=gcc&only_with_tag=gcc-4_0-branch&r1=1.795.6.6&r2=1.795.6.7 http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/testsuite/gcc.c-torture/execute/20050502-2.c.diff?cvsroot=gcc&only_with_tag=gcc-4_0-branch&r1=NONE&r2=1.1.2.1
Fixed!
Subject: Bug 21297 CVSROOT: /cvs/gcc Module name: gcc Branch: gcc-3_4-rhl-branch Changes by: jakub@gcc.gnu.org 2005-05-26 17:49:50 Modified files: gcc : ChangeLog gcc/config/i386: i386.c gcc/testsuite : ChangeLog Added files: gcc/testsuite/gcc.c-torture/execute: 20050502-2.c Log message: PR target/21297 * config/i386/i386.c (legitimize_address): When canonicalizing ASHIFT into MULT, multiply by 1 << shift_count instead of 1 << log2 (shift_count). * gcc.c-torture/execute/20050502-2.c: New test. Patches: http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/ChangeLog.diff?cvsroot=gcc&only_with_tag=gcc-3_4-rhl-branch&r1=2.2326.2.399.2.78&r2=2.2326.2.399.2.79 http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/config/i386/i386.c.diff?cvsroot=gcc&only_with_tag=gcc-3_4-rhl-branch&r1=1.635.2.8.2.11&r2=1.635.2.8.2.12 http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/testsuite/ChangeLog.diff?cvsroot=gcc&only_with_tag=gcc-3_4-rhl-branch&r1=1.3389.2.170.2.49&r2=1.3389.2.170.2.50 http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/testsuite/gcc.c-torture/execute/20050502-2.c.diff?cvsroot=gcc&only_with_tag=gcc-3_4-rhl-branch&r1=NONE&r2=1.1.8.1
Subject: Bug 21297 CVSROOT: /cvs/gcc Module name: gcc Changes by: pault@gcc.gnu.org 2005-05-29 16:02:11 Modified files: gcc/fortran : trans-array.c trans-expr.c Log message: 2005-05-29 Paul Thomas <pault@gcc.gnu.org> PR fortran/16939 PR fortran/17192 PR fortran/17193 PR fortran/17202 PR fortran/18689 PR fortran/18890 PR fortran/21297 * fortran/trans-array.c (gfc_conv_resolve_dependencies): Add string length to temp_ss for character pointer array assignments. * fortran/trans-expr.c (gfc_conv_variable): Correct errors in dereferencing of characters and character pointers. * fortran/trans-expr.c (gfc_conv_function_call): Provide string length as return argument for various kinds of handling of return. Return a char[]* temporary for character pointer functions and dereference the temporary upon return. Patches: http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/fortran/trans-array.c.diff?cvsroot=gcc&r1=1.45&r2=1.46 http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/fortran/trans-expr.c.diff?cvsroot=gcc&r1=1.44&r2=1.45