https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90257
--- Comment #15 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
I have tried:
--- gcc/cfgrtl.c (revision 270605)
+++ gcc/cfgrtl.c (working copy)
@@ -557,7 +557,8 @@ flow_active_insn_p (const rtx_insn *insn
keep the return value from being live across the entire
function. If we allow it to be skipped, we introduce the
possibility for register lifetime confusion. */
- if (GET_CODE (PATTERN (insn)) == CLOBBER
+ if ((GET_CODE (PATTERN (insn)) == CLOBBER
+ || GET_CODE (PATTERN (insn)) == USE)
&& REG_P (XEXP (PATTERN (insn), 0))
&& REG_FUNCTION_VALUE_P (XEXP (PATTERN (insn), 0)))
return true;
--- gcc/lra-spills.c (revision 270605)
+++ gcc/lra-spills.c (working copy)
@@ -740,6 +740,7 @@ lra_final_code_change (void)
int i, hard_regno;
basic_block bb;
rtx_insn *insn, *curr;
+ rtx set;
int max_regno = max_reg_num ();
for (i = FIRST_PSEUDO_REGISTER; i < max_regno; i++)
@@ -818,5 +819,19 @@ lra_final_code_change (void)
}
if (insn_change_p)
lra_update_operator_dups (id);
+
+ if ((set = single_set (insn)) != NULL
+ && REG_P (SET_SRC (set)) && REG_P (SET_DEST (set))
+ && REGNO (SET_SRC (set)) == REGNO (SET_DEST (set)))
+ {
+ /* Remove an useless move insn. IRA can generate move
+ insns involving pseudos. It is better remove them
+ earlier to speed up compiler a bit. It is also
+ better to do it here as they might not pass final RTL
+ check in LRA, (e.g. insn moving a control register
+ into itself). */
+ lra_invalidate_insn_data (insn);
+ delete_insn (insn);
+ }
}
}
on trunk, passed bootstrap/regtest and compared bootstrap with just the
lra-spills.c change.
Besides cfgrtl.o (expected) there were changes in
dwarf2asm.o
gimple-ssa-evrp.o
ipa-utils.o
reload1.o
reload.o
tree-data-ref.o
tree.o
tree-scalar-evolution.o
between the 2 stage3 gcc/ directories, but in some cases changes in debug info
only, in other cases mostly changes like:
--- tree-scalar-evolution.s_ 2019-04-29 15:24:02.029836995 +0200
+++ tree-scalar-evolution.s 2019-04-29 15:26:22.216589907 +0200
@@ -6537,7 +6537,30 @@ _ZL18find_var_scev_infoP15basic_block_de
jmp .L1172
.p2align 4,,10
.p2align 3
+.L1187:
+ movl %r9d, 36(%rbp)
+.L1176:
+ addq $24, %rsp
+ .cfi_remember_state
+ .cfi_def_cfa_offset 56
+ addq $8, %rax
+ popq %rbx
+ .cfi_def_cfa_offset 48
+ popq %rbp
+ .cfi_def_cfa_offset 40
+ popq %r12
+ .cfi_def_cfa_offset 32
+ popq %r13
+ .cfi_def_cfa_offset 24
+ popq %r14
+ .cfi_def_cfa_offset 16
+ popq %r15
+ .cfi_def_cfa_offset 8
+ ret
+ .p2align 4,,10
+ .p2align 3
.L1177:
+ .cfi_restore_state
movq %rcx, %r12
.p2align 4,,10
.p2align 3
@@ -6560,28 +6583,10 @@ _ZL18find_var_scev_infoP15basic_block_de
movl 84(%r8), %edx
movl %edx, 4(%rax)
movq %rax, (%r12)
-.L1176:
- addq $24, %rsp
- .cfi_remember_state
- .cfi_def_cfa_offset 56
- addq $8, %rax
- popq %rbx
- .cfi_def_cfa_offset 48
- popq %rbp
- .cfi_def_cfa_offset 40
- popq %r12
- .cfi_def_cfa_offset 32
- popq %r13
- .cfi_def_cfa_offset 24
- popq %r14
- .cfi_def_cfa_offset 16
- popq %r15
- .cfi_def_cfa_offset 8
- ret
+ jmp .L1176
.p2align 4,,10
.p2align 3
.L1170:
- .cfi_restore_state
movl %r9d, 36(%rbp)
testq %r12, %r12
je .L1177
@@ -6597,11 +6602,6 @@ _ZL18find_var_scev_infoP15basic_block_de
movq 8(%rbp), %rsi
movq 8(%rsp), %r8
jmp .L1163
- .p2align 4,,10
- .p2align 3
-.L1187:
- movl %r9d, 36(%rbp)
- jmp .L1176
.cfi_endproc
.section .text.unlikely
.cfi_startproc
wgere just some bbs are moved around, but the *.s length is the same. In
gimple-ssa-evrp.s there is a one byte difference in *.s size, guess just
different label numbers plus reordering.
The only larger change is ipa-utils.s, without the cfgrtl.c hunk 96603 bytes,
with that change 96479 bytes of assembly, but just 18038 vs. 18022 bytes of
.text.
