>OK for mainline? Doh, hard to believe we never checked that an insn defines a register before spitting out reg_moves for it ... nice catch.
This + /* Skip instructions that do not set a register. */ + if (set && !REG_P (SET_DEST (set))) + continue; is ok. Can you also prevent !set insns from having reg_moves? (To be updated once auto_inc insns will be supported, if they'll deserve reg_moves too.) Ayal. > > On Mon, Sep 26, 2011 at 7:31 AM, Revital Eres <revital.e...@linaro.org> wrote: >> >> Hello, >> >> The attached patch contains a fix to generate_reg_moves >> function. Currently we can generate reg-moves for stores which are later >> eliminated. This happens when we have mem dependency with distance 1 >> and as a result the number of regmoves is at least 1 based on the >> following >> calculation taken from generate_reg_moves (): >> >> if (e->distance == 1) >> nreg_moves4e = (SCHED_TIME (e->dest) - SCHED_TIME (e->src) + ii) / ii; >> >> This is an example of register move generated in such cases: >> >> reg_move = (insn 152 119 75 4 (set (reg:SI 231) >> (mem:SI (pre_modify:DI (reg:DI 215) >> (plus:DI (reg:DI 215) >> (reg:DI 171 [ ivtmp.42 ]))) [3 MEM[base: >> pretmp.27_65, index: ivtmp.42_9, offset: 0B]+0 S4 A32])) -1 >> (nil)) >> >> When not handling REG_INC instructions this was not a problem as these >> reg-moves were removes by dead code elimination. >> for example: >> >> insn 1) mem[x] = ... >> insn 2) .. = mem[y] >> >> When reg-move reg1 = mem [x] was generated mem[x] is not been used in >> insn 2 and thus reg1 could be eliminated. >> But with REG_INC this is different because the reg-move instruction >> remains and leads to bad gen. >> The attached tescase capture this case. >> >> Tested and bootstrap with patch 2 on ppc64-redhat-linux >> enabling SMS on loops with SC 1. On arm-linux-gnueabi bootstrap c on >> top of the set of patches that support do-loop pattern >> (http://gcc.gnu.org/ml/gcc-patches/2011-07/msg01807.html) which solves >> the bootstrap failure on ARM with SMS flags. >> >> OK for mainline? >> >> Thanks, >> Revital >> >> gcc/ >> * modulo-sched.c (generate_reg_moves): Skip instructions that >> do not set a register. >> >> >> testsuite/ >> * gcc.dg/sms-10.c: New file. >
