https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64213
--- Comment #5 from rguenther at suse dot de <rguenther at suse dot de> --- On Tue, 9 Dec 2014, ubizjak at gmail dot com wrote: > https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64213 > > --- Comment #4 from Uroš Bizjak <ubizjak at gmail dot com> --- > One of several testsuite failures (with non-bootstrapped compiler) is: > > FAIL: gcc.c-torture/execute/20020805-1.c -Os execution test > > --cut here-- > extern void abort (void); > extern void exit (int); > > void check (unsigned int m) > { > if (m != (unsigned int) -1) > abort (); > } > > unsigned int n = 1; > > int main (void) > { > unsigned int m; > m = (1 | (2 - n)) | (-n); > check (m); > exit (0); > } > --cut here-- > > So, the difference between trunk (+) and trunk with reverted patch (-) starts > at _.214r.combine, where "check" function gets miscompiled: > > 4: NOTE_INSN_BASIC_BLOCK 2 > 2: NOTE_INSN_DELETED > 3: NOTE_INSN_FUNCTION_BEG > - 6: r71:DI=zero_extend($16:SI) > - REG_DEAD $16:DI > + 6: NOTE_INSN_DELETED > 7: r73:DI=0xffffffffffffffff > 8: r72:DI=r73:DI 0>>0x20 > REG_DEAD r73:DI > REG_EQUAL 0xffffffff > - 9: r74:DI=r71:DI==r72:DI > + 9: r74:DI=$16:DI==r72:DI > + REG_DEAD $16:DI > REG_DEAD r72:DI > - REG_DEAD r71:DI > 10: pc={(r74:DI!=0)?L16:pc} > REG_DEAD r74:DI > REG_BR_PROB 9996 > > This results in an asm code difference, where needed SI->DI zero_extend is > missing: > > @@ -18,7 +18,6 @@ > lda $1,-1($31) > lda $30,-16($30) > .cfi_def_cfa_offset 16 > - zapnot $16,15,$16 > srl $1,32,$1 > stq $26,0($30) > .cfi_offset 26, -16 > > I propose to revert H.J.'s patch for PR64037. Agreed and approved. Please make sure to re-open bugs that were fixed by the patch.
