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author | Roger Sayle <roger@nextmovesoftware.com> | 2022-06-07 10:09:49 +0100 |
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committer | Roger Sayle <roger@nextmovesoftware.com> | 2022-06-07 10:09:49 +0100 |
commit | c00e1e3aa5ae62a991d105d309061d12f6a8764f (patch) | |
tree | 75bcd6c0007a3666c4b6e0603b2e797f9045edab /gcc/calls.cc | |
parent | cef3f69c2f4cbc05aa3ec00f2fdbacfa8ca1d303 (diff) | |
download | gcc-c00e1e3aa5ae62a991d105d309061d12f6a8764f.zip gcc-c00e1e3aa5ae62a991d105d309061d12f6a8764f.tar.gz gcc-c00e1e3aa5ae62a991d105d309061d12f6a8764f.tar.bz2 |
PR middle-end/105853: Call store_constructor directly from calls.cc.
This patch fixes both ICE regressions PR middle-end/105853 and
PR target/105856 caused by my recent patch to expand small const structs
as immediate constants. That patch updated code generation in three
places: two in expr.cc that call store_constructor directly, and the
third in calls.cc's load_register_parameters that expands its CONSTRUCTOR
via expand_expr, as store_constructor is local/static to expr.cc, and
the "public" API, should usually simply forward the constructor to the
appropriate store_constructor function.
Alas, despite the clean regression testing on multiple targets, the above
ICEs show that expand_expr isn't a suitable proxy for store_constructor,
and things that (I'd assumed) shouldn't affect how/whether a struct is
placed in a register [such as whether the struct is considered packed/
aligned or not] actually interfere with the optimization that is being
attempted.
The (proposed) solution is to export store_constructor (and it's helper
function int_expr_size) from expr.cc, by removing their static qualifier
and prototyping both functions in expr.h, so they can be called directly
from load_register_parameters in calls.cc. This cures both ICEs, but
almost as importantly improves code generation over GCC 12.
For PR 105853, GCC 12 generates:
compose_nd_na_ipv6_src:
movzx eax, WORD PTR eth_addr_zero[rip+2]
movzx edx, WORD PTR eth_addr_zero[rip]
movzx edi, WORD PTR eth_addr_zero[rip+4]
sal rax, 16
or rax, rdx
sal rdi, 32
or rdi, rax
xor eax, eax
jmp packet_set_nd
eth_addr_zero: .zero 6
where now (with this fix) GCC 13 generates:
compose_nd_na_ipv6_src:
xorl %edi, %edi
xorl %eax, %eax
jmp packet_set_nd
Likewise, for PR 105856 on ARM, we'd previously generate:
g_329_3:
movw r3, #:lower16:.LANCHOR0
movt r3, #:upper16:.LANCHOR0
ldr r0, [r3]
b func_19
but with this optimization we now generate:
g_329_3:
mov r0, #6
b func_19
2022-06-07 Roger Sayle <roger@nextmovesoftware.com>
gcc/ChangeLog
PR middle-end/105853
PR target/105856
* calls.cc (load_register_parameters): Call store_constructor
and int_expr_size directly instead of expanding via expand_expr.
* expr.cc (static void store_constructor): Don't prototype here.
(static HOST_WIDE_INT int_expr_size): Likewise.
(store_constructor): No longer static.
(int_expr_size): Likewise, no longer static.
* expr.h (store_constructor): Prototype here.
(int_expr_size): Prototype here.
gcc/testsuite/ChangeLog
PR middle-end/105853
PR target/105856
* gcc.dg/pr105853.c: New test case.
* gcc.dg/pr105856.c: New test case.
Diffstat (limited to 'gcc/calls.cc')
-rw-r--r-- | gcc/calls.cc | 7 |
1 files changed, 4 insertions, 3 deletions
diff --git a/gcc/calls.cc b/gcc/calls.cc index a4336c1..f4e1299 100644 --- a/gcc/calls.cc +++ b/gcc/calls.cc @@ -2186,10 +2186,11 @@ load_register_parameters (struct arg_data *args, int num_actuals, && immediate_const_ctor_p (DECL_INITIAL (tree_value))) { rtx target = gen_reg_rtx (word_mode); - rtx x = expand_expr (DECL_INITIAL (tree_value), - target, word_mode, EXPAND_NORMAL); + store_constructor (DECL_INITIAL (tree_value), target, 0, + int_expr_size (DECL_INITIAL (tree_value)), + false); reg = gen_rtx_REG (word_mode, REGNO (reg)); - emit_move_insn (reg, x); + emit_move_insn (reg, target); } else if (partial == 0 || args[i].pass_on_stack) { |