Hi,
"Kewen.Lin" <li...@linux.ibm.com> writes: > Hi, > > on 2023/10/25 10:00, Jiufu Guo wrote: >> Hi, >> >> Sometimes, a complicated constant is built via 3(or more) >> instructions to build. Generally speaking, it would not be >> as faster as loading it from the constant pool (as a few >> discussions in PR63281). > > I may miss some previous discussions, but I'm curious why we > chose ">=3" here, as https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63281#c9 > which indicates that more than 3 (>3) should be considered > with this change. Thanks a lot for your great patience for reading the history! Yes, there are some discussions about "> 3" vs. "> 2". - In theory, "ld" is one instruction. If consider "address/toc" adjust, we may count it as 2 instructions. "pld" may need less cycles. - As test, it seems "> 2" could get better/stable runtime result during testing SPEC2017. > >> >> For the concern that I raised in: >> https://gcc.gnu.org/pipermail/gcc-patches/2022-August/599676.html >> The micro-cases would not be the major concern. Because as >> Segher explained in: >> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63281#c18 >> It would just be about the benchmark method. >> >> As tested on spec2017, for visible performance changes, we >> can find the runtime improvement on 500.perlbench_r about >> ~1.8% (-O2) when support loading complicates constant from >> constant pool. And no visible performance recession on >> other benchmarks. > > The improvement on 500.perlbench_r looks to match what PR63281 > mentioned, nice! I'm curious that which options and which kinds > of CPUs have you tested with? Since this is a general change, > I'd expect we can test with P8/P9/P10 at O2/O3 (or Ofast) at > least. Great advice! Thanks for pointing this! A few months ago, P8/P9/P10 are tested. While this time, I rerun SPEC2017 on P10 for -O2 and -O3. More test on latest code would be better. BR, Jeff (Jiufu Guo) > > BR, > Kewen > >> >> Boostrap & regtest pass on ppc64{,le}. >> Is this ok for trunk? >> >> BR, >> Jeff (Jiufu Guo) >> >> PR target/63281 >> >> gcc/ChangeLog: >> >> * config/rs6000/rs6000.cc (rs6000_emit_set_const): Update to split >> complicate constant to memory. >> >> gcc/testsuite/ChangeLog: >> >> * gcc.target/powerpc/const_anchors.c: Update to test final-rtl. >> * gcc.target/powerpc/parall_5insn_const.c: Update to keep original test >> point. >> * gcc.target/powerpc/pr106550.c: Likewise.. >> * gcc.target/powerpc/pr106550_1.c: Likewise. >> * gcc.target/powerpc/pr87870.c: Update according to latest behavior. >> * gcc.target/powerpc/pr93012.c: Likewise. >> >> --- >> gcc/config/rs6000/rs6000.cc | 16 ++++++++++++++++ >> .../gcc.target/powerpc/const_anchors.c | 5 ++--- >> .../gcc.target/powerpc/parall_5insn_const.c | 14 ++++++++++++-- >> gcc/testsuite/gcc.target/powerpc/pr106550.c | 17 +++++++++++++++-- >> gcc/testsuite/gcc.target/powerpc/pr106550_1.c | 15 +++++++++++++-- >> gcc/testsuite/gcc.target/powerpc/pr87870.c | 5 ++++- >> gcc/testsuite/gcc.target/powerpc/pr93012.c | 4 +++- >> 7 files changed, 65 insertions(+), 11 deletions(-) >> >> diff --git a/gcc/config/rs6000/rs6000.cc b/gcc/config/rs6000/rs6000.cc >> index 4690384cdbe..b9562f1ea0f 100644 >> --- a/gcc/config/rs6000/rs6000.cc >> +++ b/gcc/config/rs6000/rs6000.cc >> @@ -10292,6 +10292,22 @@ rs6000_emit_set_const (rtx dest, rtx source) >> c = sext_hwi (c, 32); >> emit_move_insn (lo, GEN_INT (c)); >> } >> + >> + /* If it can be stored to the constant pool and profitable. */ >> + else if (base_reg_operand (dest, mode) >> + && num_insns_constant (source, mode) > 2) >> + { >> + rtx sym = force_const_mem (mode, source); >> + if (TARGET_TOC && SYMBOL_REF_P (XEXP (sym, 0)) >> + && use_toc_relative_ref (XEXP (sym, 0), mode)) >> + { >> + rtx toc = create_TOC_reference (XEXP (sym, 0), copy_rtx (dest)); >> + sym = gen_const_mem (mode, toc); >> + set_mem_alias_set (sym, get_TOC_alias_set ()); >> + } >> + >> + emit_insn (gen_rtx_SET (dest, sym)); >> + } >> else >> rs6000_emit_set_long_const (dest, c); >> break; >> diff --git a/gcc/testsuite/gcc.target/powerpc/const_anchors.c >> b/gcc/testsuite/gcc.target/powerpc/const_anchors.c >> index 542e2674b12..188744165f2 100644 >> --- a/gcc/testsuite/gcc.target/powerpc/const_anchors.c >> +++ b/gcc/testsuite/gcc.target/powerpc/const_anchors.c >> @@ -1,5 +1,5 @@ >> /* { dg-do compile { target has_arch_ppc64 } } */ >> -/* { dg-options "-O2" } */ >> +/* { dg-options "-O2 -fdump-rtl-final" } */ >> >> #define C1 0x2351847027482577ULL >> #define C2 0x2351847027482578ULL >> @@ -16,5 +16,4 @@ void __attribute__ ((noinline)) foo1 (long long *a, long >> long b) >> if (b) >> *a++ = C2; >> } >> - >> -/* { dg-final { scan-assembler-times {\maddi\M} 2 } } */ >> +/* { dg-final { scan-rtl-dump-times {\madddi3\M} 2 "final" } } */ >> diff --git a/gcc/testsuite/gcc.target/powerpc/parall_5insn_const.c >> b/gcc/testsuite/gcc.target/powerpc/parall_5insn_const.c >> index e3a9a7264cf..df0690b90be 100644 >> --- a/gcc/testsuite/gcc.target/powerpc/parall_5insn_const.c >> +++ b/gcc/testsuite/gcc.target/powerpc/parall_5insn_const.c >> @@ -9,8 +9,18 @@ >> void __attribute__ ((noinline)) foo (unsigned long long *a) >> { >> /* 2 lis + 2 ori + 1 rldimi for each constant. */ >> - *a++ = 0x800aabcdc167fa16ULL; >> - *a++ = 0x7543a876867f616ULL; >> + { >> + register long long d asm("r0") = 0x800aabcdc167fa16ULL; >> + long long n; >> + asm("mr %0, %1" : "=r"(n) : "r"(d)); >> + *a++ = n; >> + } >> + { >> + register long long d asm("r0") = 0x7543a876867f616ULL; >> + long long n; >> + asm("mr %0, %1" : "=r"(n) : "r"(d)); >> + *a++ = n; >> + } >> } >> >> long long A[] = {0x800aabcdc167fa16ULL, 0x7543a876867f616ULL}; >> diff --git a/gcc/testsuite/gcc.target/powerpc/pr106550.c >> b/gcc/testsuite/gcc.target/powerpc/pr106550.c >> index 74e395331ab..5eca2b2f701 100644 >> --- a/gcc/testsuite/gcc.target/powerpc/pr106550.c >> +++ b/gcc/testsuite/gcc.target/powerpc/pr106550.c >> @@ -1,12 +1,25 @@ >> /* PR target/106550 */ >> /* { dg-options "-O2 -mdejagnu-cpu=power10" } */ >> /* { dg-require-effective-target power10_ok } */ >> +/* { dg-require-effective-target has_arch_ppc64 } */ >> >> void >> foo (unsigned long long *a) >> { >> - *a++ = 0x020805006106003; /* pli+pli+rldimi */ >> - *a++ = 0x2351847027482577;/* pli+pli+rldimi */ >> + { >> + /* pli+pli+rldimi */ >> + register long long d asm("r0") = 0x020805006106003ULL; >> + long long n; >> + asm("mr %0, %1" : "=r"(n) : "r"(d)); >> + *a++ = n; >> + } >> + { >> + /* pli+pli+rldimi */ >> + register long long d asm("r0") = 0x2351847027482577ULL; >> + long long n; >> + asm("mr %0, %1" : "=r"(n) : "r"(d)); >> + *a++ = n; >> + } >> } >> >> /* { dg-final { scan-assembler-times {\mpli\M} 4 } } */ >> diff --git a/gcc/testsuite/gcc.target/powerpc/pr106550_1.c >> b/gcc/testsuite/gcc.target/powerpc/pr106550_1.c >> index 7e709fcf9d8..11878d893a4 100644 >> --- a/gcc/testsuite/gcc.target/powerpc/pr106550_1.c >> +++ b/gcc/testsuite/gcc.target/powerpc/pr106550_1.c >> @@ -12,8 +12,19 @@ foo (unsigned long long *a) >> asm("cntlzd %0, %1" : "=r"(n) : "r"(d)); >> *a++ = n; >> >> - *a++ = 0x235a8470a7480000ULL; /* pli+sldi+oris */ >> - *a++ = 0x23a184700000b677ULL; /* pli+sldi+ori */ >> + { >> + register long long d asm("r0") = 0x235a8470a7480000ULL; /* >> pli+sldi+oris */ >> + long long n; >> + asm("cntlzd %0, %1" : "=r"(n) : "r"(d)); >> + *a++ = n; >> + } >> + >> + { >> + register long long d asm("r0") = 0x23a184700000b677ULL; /* pli+sldi+ori >> */ >> + long long n; >> + asm("cntlzd %0, %1" : "=r"(n) : "r"(d)); >> + *a++ = n; >> + } >> } >> >> /* { dg-final { scan-assembler-times {\mpli\M} 3 } } */ >> diff --git a/gcc/testsuite/gcc.target/powerpc/pr87870.c >> b/gcc/testsuite/gcc.target/powerpc/pr87870.c >> index d2108ac3386..5fee06744ae 100644 >> --- a/gcc/testsuite/gcc.target/powerpc/pr87870.c >> +++ b/gcc/testsuite/gcc.target/powerpc/pr87870.c >> @@ -25,4 +25,7 @@ test3 (void) >> return ((__int128)0xdeadbeefcafebabe << 64) | 0xfacefeedbaaaaaad; >> } >> >> -/* { dg-final { scan-assembler-not {\mld\M} } } */ >> +/* test3 using "ld" to load the value for r3 and r4. >> + test0, test1 and test2 are using "li". */ >> +/* { dg-final { scan-assembler-times {\mp?ld\M} 2 } } */ >> +/* { dg-final { scan-assembler-times {\mli\M} 6 } } */ >> diff --git a/gcc/testsuite/gcc.target/powerpc/pr93012.c >> b/gcc/testsuite/gcc.target/powerpc/pr93012.c >> index 4f764d0576f..87ce0b49b23 100644 >> --- a/gcc/testsuite/gcc.target/powerpc/pr93012.c >> +++ b/gcc/testsuite/gcc.target/powerpc/pr93012.c >> @@ -10,4 +10,6 @@ unsigned long long mskh1() { return 0xffff9234ffff9234ULL; >> } >> unsigned long long mskl1() { return 0x2bcdffff2bcdffffULL; } >> unsigned long long mskse() { return 0xffff1234ffff1234ULL; } >> >> -/* { dg-final { scan-assembler-times {\mrldimi\M} 7 } } */ >> +/* { dg-final { scan-assembler-times {\mrldimi\M} 7 { target { >> has_arch_pwr10 } } } } */ >> +/* { dg-final { scan-assembler-times {\mrldimi\M} 3 { target { ! >> has_arch_pwr10 } } } } */ >> +/* { dg-final { scan-assembler-times {\mp?ld\M} 4 { target { ! >> has_arch_pwr10 } } } } */
