Andreas Geißler schrieb:
Hi. I need your help again. I wrote my own backend for the gcc-4.6.2 and with your help it works nearly perfectly. But i have a problem with the test case pr26180.c. The compiler does not load the register, which is used for the comparison. And i don't get why. C-Code: ... x2 = (x > 0 ? x : (-x)); ... Wrong translated assembler code: ...
Assembler don't tell anything; look at TL dump with -da, -fdump-rtl-all or -fdump-rtl-all-details.
You might also want so set -dp and / or -dP and / or -fverbose-asm to see insns along with assembly.
The translation works also correctly if i use "if else" instead of "?:". So i you would like to ask you, which pattern is related to "x2 = (x > 0 ? x : (-x));"
Who knows if not you? That depends on your backend: Maybe absXX2, maybe movXXcc, maybe jumping around and movXX and negXX2, ...
or where i should search for this problem.
Look at .expand dump and track until where it gets wrong. Presumably a wrong expander, wrong constraints (missing early clobber), wrong peephole, whatever.
Johann
