Thanks, Bin and Richard -- I am out of the office until Tuesday, so will review when I get back. Bin, please CC me on SLSR patches as otherwise I might miss them. Thanks!
Bill On 5/16/19 6:37 AM, Richard Biener wrote: > On Wed, May 15, 2019 at 6:30 AM bin.cheng <bin.ch...@linux.alibaba.com> wrote: >> Hi, >> As noted in PR57534 comment #33, SLSR currently doesn't strength reduce >> memory >> references in reported cases, which conflicts with its comment at the >> beginning of file. >> The main reason is in functions slsr_process_ref and restructure_reference >> which >> rejects MEM_REF by handled_compoenent_p in the first place. This patch >> identifies >> and creates CAND_REF for MEM_REF by restructuring base/offset. >> >> Note the patch only affects cases with multiple reducible MEM_REF. >> >> Also note, with this patch, [base + cst_offset] addressing mode would be >> generally >> preferred. I need to adjust three existing tests: >> * gcc.dg/tree-ssa/isolate-5.c >> * gcc.dg/tree-ssa/ssa-hoist-4.c >> Though address computation is reduced out of memory reference, the generated >> assembly is not worsened. >> >> * gcc.dg/tree-ssa/slsr-3.c >> The generated assembly has two more instructions: >> < movslq %edx, %rcx >> < movl (%rsi,%rcx,4), %r9d >> < leaq 0(,%rcx,4), %rax >> < leal 2(%r9), %r8d >> < movl %r8d, (%rdi,%rcx,4) >> < movl 4(%rsi,%rax), %ecx >> < addl $2, %ecx >> < movl %ecx, 4(%rdi,%rax) >> < movl 8(%rsi,%rax), %ecx >> < addl $2, %ecx >> < movl %ecx, 8(%rdi,%rax) >> < movl 12(%rsi,%rax), %ecx >> < addl $2, %ecx >> < movl %ecx, 12(%rdi,%rax) >> --- >>> movslq %edx, %rax >>> salq $2, %rax >>> addq %rax, %rsi >>> addq %rax, %rdi >>> movl (%rsi), %eax >>> addl $2, %eax >>> movl %eax, (%rdi) >>> movl 4(%rsi), %eax >>> addl $2, %eax >>> movl %eax, 4(%rdi) >>> movl 8(%rsi), %eax >>> addl $2, %eax >>> movl %eax, 8(%rdi) >>> movl 12(%rsi), %eax >>> addl $2, %eax >>> movl %eax, 12(%rdi) >> Seems to me this is not deteriorating and "salq" can be saved by two forward >> propagation. >> >> Bootstrap and test on x86_64, any comments? > The idea is good I think and the result above as well. Leaving for Bill > to have a look as well, otherwise OK. > > Thanks, > Richard. > >> Thanks, >> bin >> >> 2019-05-15 Bin Cheng <bin.ch...@linux.alibaba.com> >> >> PR tree-optimization/57534 >> * gimple-ssa-strength-reduction.c (restructure_base_offset): New. >> (restructure_reference): Call restructure_base_offset when offset is >> NULL. >> (slsr_process_ref): Handle MEM_REF. >> >> 2018-05-15 Bin Cheng <bin.ch...@linux.alibaba.com> >> >> PR tree-optimization/57534 >> * gcc.dg/tree-ssa/pr57534.c: New test. >> * gcc.dg/tree-ssa/isolate-5.c: Adjust checking strings. >> * gcc.dg/tree-ssa/slsr-3.c: Ditto. >> * gcc.dg/tree-ssa/ssa-hoist-4.c: Ditto.
