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author | Roger Sayle <roger@nextmovesoftware.com> | 2023-06-13 17:20:31 +0100 |
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committer | Roger Sayle <roger@nextmovesoftware.com> | 2023-06-13 17:20:31 +0100 |
commit | 40eafcd83d6ee644ec48985fd5a9696921ea10e7 (patch) | |
tree | 15ad92061909804f4b3d0ad83d6492e823680772 /gcc | |
parent | 06a0f07220cea449b4683f9bb9cce2e5de1e5a35 (diff) | |
download | gcc-40eafcd83d6ee644ec48985fd5a9696921ea10e7.zip gcc-40eafcd83d6ee644ec48985fd5a9696921ea10e7.tar.gz gcc-40eafcd83d6ee644ec48985fd5a9696921ea10e7.tar.bz2 |
Avoid duplicate vector initializations during RTL expansion.
This middle-end patch avoids some redundant RTL for vector initialization
during RTL expansion. For the simple test case:
typedef __int128 v1ti __attribute__ ((__vector_size__ (16)));
__int128 key;
v1ti foo() {
return (v1ti){key};
}
the middle-end currently expands:
(set (reg:V1TI 85) (const_vector:V1TI [ (const_int 0) ]))
(set (reg:V1TI 85) (mem/c:V1TI (symbol_ref:DI ("key"))))
where we create a dead instruction that initializes the vector to zero,
immediately followed by a set of the entire vector. This patch skips
this zeroing instruction when the vector has only a single element.
It also updates the code to indicate when we've cleared the vector,
so that we don't need to initialize zero elements.
2023-06-13 Roger Sayle <roger@nextmovesoftware.com>
gcc/ChangeLog
* expr.cc (store_constructor) <case VECTOR_TYPE>: Don't bother
clearing vectors with only a single element. Set CLEARED if the
vector was initialized to zero.
Diffstat (limited to 'gcc')
-rw-r--r-- | gcc/expr.cc | 7 |
1 files changed, 5 insertions, 2 deletions
diff --git a/gcc/expr.cc b/gcc/expr.cc index 868fa6e..62cd8fa 100644 --- a/gcc/expr.cc +++ b/gcc/expr.cc @@ -7531,8 +7531,11 @@ store_constructor (tree exp, rtx target, int cleared, poly_int64 size, } /* Inform later passes that the old value is dead. */ - if (!cleared && !vector && REG_P (target)) - emit_move_insn (target, CONST0_RTX (mode)); + if (!cleared && !vector && REG_P (target) && maybe_gt (n_elts, 1u)) + { + emit_move_insn (target, CONST0_RTX (mode)); + cleared = 1; + } if (MEM_P (target)) alias = MEM_ALIAS_SET (target); |