subject:"\[PATCH v3\] xtensa\: Eliminate the use of callee\-saved register that saves and restores only once"

Re: [PATCH v3] xtensa: Eliminate the use of callee-saved register that saves and restores only once

2023-01-18 Thread Max Filippov via Gcc-patches

Hi Suwa-san,

On Tue, Jan 17, 2023 at 8:23 PM Takayuki 'January June' Suwa
 wrote:
> In the case of the CALL0 ABI, values that must be retained before and
> after function calls are placed in the callee-saved registers (A12
> through A15) and referenced later.  However, it is often the case that
> the save and the reference are each only once and a simple register-
> register move (the frame pointer is needed to recover the stack pointer
> and must be excluded).
>
> e.g. in the following example, if there are no other occurrences of
> register A14:
>
> ;; before
> ; prologue {
>   ...
> s32i.n  a14, sp, 16
>   ...
> ; } prologue
>   ...
> mov.n   a14, a6
>   ...
> call0   foo
>   ...
> mov.n   a8, a14
>   ...
> ; epilogue {
>   ...
> l32i.n  a14, sp, 16
>   ...
> ; } epilogue
>
> It can be possible like this:
>
> ;; after
> ; prologue {
>   ...
> (deleted)
>   ...
> ; } prologue
>   ...
> s32i.n  a6, sp, 16
>   ...
> call0   foo
>   ...
> l32i.n  a8, sp, 16
>   ...
> ; epilogue {
>   ...
> (deleted)
>   ...
> ; } epilogue
>
> This patch introduces a new peephole2 pattern that implements the above.
>
> gcc/ChangeLog:
>
> * config/xtensa/xtensa.md: New peephole2 pattern that eliminates
> the use of callee-saved register that saves and restores only once
> for other register, by using its stack slot directly.
> ---
>  gcc/config/xtensa/xtensa.md | 62 +
>  1 file changed, 62 insertions(+)

This change introduces a bunch of different test failures:

FAIL: gcc.c-torture/execute/builtins/strpbrk.c execution,  -O2
FAIL: gcc.c-torture/execute/builtins/strpbrk.c execution,  -O3 -g
FAIL: gcc.c-torture/execute/builtins/strpbrk.c execution,  -Os
FAIL: gcc.c-torture/execute/builtins/strpbrk.c execution,  -O2 -flto
-fno-use-linker-plugin -flto-partition=none
FAIL: gcc.c-torture/execute/builtins/strstr-asm.c execution,  -Os
FAIL: gcc.c-torture/execute/20001130-1.c   -Os  execution test
FAIL: gcc.c-torture/execute/20040311-1.c   -O2  execution test
FAIL: gcc.c-torture/execute/20040311-1.c   -O3 -g  execution test
FAIL: gcc.c-torture/execute/20040311-1.c   -O2 -flto
-fno-use-linker-plugin -flto-partition=none  execution test
FAIL: gcc.c-torture/execute/20121108-1.c   -O2  execution test
FAIL: gcc.c-torture/execute/20121108-1.c   -O3 -fomit-frame-pointer
-funroll-loops -fpeel-loops -ftracer -finline-functions  execution
test
FAIL: gcc.c-torture/execute/20121108-1.c   -O3 -g  execution test
FAIL: gcc.c-torture/execute/20121108-1.c   -Os  execution test
FAIL: gcc.c-torture/execute/20121108-1.c   -O2 -flto
-fno-use-linker-plugin -flto-partition=none  execution test
FAIL: gcc.c-torture/execute/20121108-1.c   -O2 -flto
-fuse-linker-plugin -fno-fat-lto-objects  execution test
FAIL: gcc.c-torture/execute/20140622-1.c   -O2  execution test
FAIL: gcc.c-torture/execute/20140622-1.c   -O3 -g  execution test
FAIL: gcc.c-torture/execute/20140622-1.c   -O2 -flto
-fno-use-linker-plugin -flto-partition=none  execution test
FAIL: gcc.c-torture/execute/20141022-1.c   -O2  execution test
FAIL: gcc.c-torture/execute/20141022-1.c   -O3 -fomit-frame-pointer
-funroll-loops -fpeel-loops -ftracer -finline-functions  execution
test
FAIL: gcc.c-torture/execute/20141022-1.c   -O3 -g  execution test
FAIL: gcc.c-torture/execute/20141022-1.c   -O2 -flto
-fno-use-linker-plugin -flto-partition=none  execution test
FAIL: gcc.c-torture/execute/20141022-1.c   -O2 -flto
-fuse-linker-plugin -fno-fat-lto-objects  execution test
FAIL: gcc.c-torture/execute/20141107-1.c   -O2 -flto
-fuse-linker-plugin -fno-fat-lto-objects  execution test
FAIL: gcc.c-torture/execute/961213-1.c   -Os  execution test
FAIL: gcc.c-torture/execute/builtin-bitops-1.c   -Os  execution test
FAIL: gcc.c-torture/execute/cvt-1.c   -O2  execution test
FAIL: gcc.c-torture/execute/cvt-1.c   -O3 -g  execution test
FAIL: gcc.c-torture/execute/cvt-1.c   -Os  execution test
FAIL: gcc.c-torture/execute/cvt-1.c   -O2 -flto -fno-use-linker-plugin
-flto-partition=none  execution test
FAIL: gcc.c-torture/execute/pr40747.c   -O2  execution test
FAIL: gcc.c-torture/execute/pr40747.c   -O3 -g  execution test
FAIL: gcc.c-torture/execute/pr40747.c   -O2 -flto
-fno-use-linker-plugin -flto-partition=none  execution test
FAIL: gcc.c-torture/execute/pr60960.c   -O2  execution test
FAIL: gcc.c-torture/execute/pr60960.c   -O3 -g  execution test
FAIL: gcc.c-torture/execute/pr60960.c   -O2 -flto
-fno-use-linker-plugin -flto-partition=none  execution test
FAIL: gcc.c-torture/execute/pr60960.c   -O2 -flto -fuse-linker-plugin
-fno-fat-lto-objects  execution test
FAIL: gcc.c-torture/execute/ieee/fp-cmp-5.c execution,  -O2
FAIL: gcc.c-torture/execute/ieee/fp-cmp-5.c execution,  -O3
-fomit-frame-pointer -funroll-loops -fpeel-loops -ftracer
-finline-functions
FAIL: gcc.c-torture/execute/ieee/fp-cmp-5.c execution,  -O3 -g

[PATCH v3] xtensa: Eliminate the use of callee-saved register that saves and restores only once

2023-01-17 Thread Takayuki 'January June' Suwa via Gcc-patches

On 2023/01/17 20:23, Max Filippov wrote:
> Hi Suwa-san,
Hi!

> There's still a few regressions in tests with -fcompare-debug because
> code generated with -g and without it is different:
> E.g. check the following test with -g0 and -g:
Again debug_insn is the problem...

=
In the case of the CALL0 ABI, values that must be retained before and
after function calls are placed in the callee-saved registers (A12
through A15) and referenced later.  However, it is often the case that
the save and the reference are each only once and a simple register-
register move (the frame pointer is needed to recover the stack pointer
and must be excluded).

e.g. in the following example, if there are no other occurrences of
register A14:

;; before
; prologue {
  ...
s32i.n  a14, sp, 16
  ...
; } prologue
  ...
mov.n   a14, a6
  ...
call0   foo
  ...
mov.n   a8, a14
  ...
; epilogue {
  ...
l32i.n  a14, sp, 16
  ...
; } epilogue

It can be possible like this:

;; after
; prologue {
  ...
(deleted)
  ...
; } prologue
  ...
s32i.n  a6, sp, 16
  ...
call0   foo
  ...
l32i.n  a8, sp, 16
  ...
; epilogue {
  ...
(deleted)
  ...
; } epilogue

This patch introduces a new peephole2 pattern that implements the above.

gcc/ChangeLog:

* config/xtensa/xtensa.md: New peephole2 pattern that eliminates
the use of callee-saved register that saves and restores only once
for other register, by using its stack slot directly.
---
 gcc/config/xtensa/xtensa.md | 62 +
 1 file changed, 62 insertions(+)

diff --git a/gcc/config/xtensa/xtensa.md b/gcc/config/xtensa/xtensa.md
index 98f3c468f8b..2f3b2256d8b 100644
--- a/gcc/config/xtensa/xtensa.md
+++ b/gcc/config/xtensa/xtensa.md
@@ -3024,3 +3024,65 @@ FALLTHRU:;
   operands[1] = GEN_INT (imm0);
   operands[2] = GEN_INT (imm1);
 })
+
+(define_peephole2
+  [(set (match_operand:SI 0 "register_operand")
+   (match_operand:SI 1 "reload_operand"))]
+  "!TARGET_WINDOWED_ABI && df
+   && epilogue_contains (insn)
+   && ! call_used_or_fixed_reg_p (REGNO (operands[0]))
+   && (!frame_pointer_needed
+   || REGNO (operands[0]) != HARD_FRAME_POINTER_REGNUM)"
+  [(const_int 0)]
+{
+  rtx reg = operands[0], pattern;
+  rtx_insn *insnP = NULL, *insnS = NULL, *insnR = NULL;
+  df_ref ref;
+  rtx_insn *insn;
+  for (ref = DF_REG_DEF_CHAIN (REGNO (reg));
+   ref; ref = DF_REF_NEXT_REG (ref))
+if (DF_REF_CLASS (ref) != DF_REF_REGULAR
+   || ! NONJUMP_INSN_P (insn = DF_REF_INSN (ref)))
+  continue;
+else if (insn == curr_insn)
+  continue;
+else if (GET_CODE (pattern = PATTERN (insn)) == SET
+&& rtx_equal_p (SET_DEST (pattern), reg)
+&& REG_P (SET_SRC (pattern)))
+  {
+   if (insnS)
+ FAIL;
+   insnS = insn;
+   continue;
+  }
+else
+  FAIL;
+  for (ref = DF_REG_USE_CHAIN (REGNO (reg));
+   ref; ref = DF_REF_NEXT_REG (ref))
+if (DF_REF_CLASS (ref) != DF_REF_REGULAR
+   || ! NONJUMP_INSN_P (insn = DF_REF_INSN (ref)))
+  continue;
+else if (prologue_contains (insn))
+  {
+   insnP = insn;
+   continue;
+  }
+else if (GET_CODE (pattern = PATTERN (insn)) == SET
+&& rtx_equal_p (SET_SRC (pattern), reg)
+&& REG_P (SET_DEST (pattern)))
+  {
+   if (insnR)
+ FAIL;
+   insnR = insn;
+   continue;
+  }
+else
+  FAIL;
+  if (!insnP || !insnS || !insnR)
+FAIL;
+  SET_DEST (PATTERN (insnS)) = copy_rtx (operands[1]);
+  df_insn_rescan (insnS);
+  SET_SRC (PATTERN (insnR)) = copy_rtx (operands[1]);
+  df_insn_rescan (insnR);
+  set_insn_deleted (insnP);
+})
-- 
2.30.2

Re: [PATCH v3] xtensa: Eliminate the use of callee-saved register that saves and restores only once

[PATCH v3] xtensa: Eliminate the use of callee-saved register that saves and restores only once

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