Hi Yvan, On 18/03/15 10:19, Yvan Roux wrote:
Hi,This is a fix for PR64208 where LRA loops when dealing with iwmmxt_arm_movdi insn. As explain in the PR, the issue was introduced on trunk and 4.9 branch by fix of PR rtl-optimization/60969 and then workaround by r211798 (-fuse-caller-save enable for ARM). The changes in IRA cost made by PR60969, changed the register class of this insn output from GENERAL_REGS to IWMMXT_REGS, and the redundancies in the insn pattern alternatives description force LRA to reload the pseudo, which generates the same iwmmxt_arm_movdi insn, which can't be resolved, and so on ... Removing the redundancies fixes the issue, as LRA find that alternative 8 (Uy => y) matches. This issue is present in 4.9 branch, but latent on trunk (the clobbering of IP and CC information added during -fuse-caller-save patch changed the register allocation). Cross compiled and regression tested on ARM targets (but not on an IWMMXT one), is it ok for trunk and 4.9 branch ? Rq: I think that adding IP and CC clobbers to CALL_INSN_FUNCTION_USAGE, as specified by AAPCS, in 4.9 branch is something we need too, I've a patch for that if you agree on that. Thanks, Yvan 2105-03-17 Yvan Roux <yvan.r...@linaro.org> PR target/64208 * config/arm/iwmmxt.md ("*iwmmxt_arm_movdi"): Cleanup redundant alternatives.
As a general note, I think this patch should include the testcase from the PR.
I can see that it's fairly self-contained. Cheers, Kyrill
