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| author | Roger Sayle <roger@nextmovesoftware.com> | 2022-02-22 12:32:22 +0000 |
|---|---|---|
| committer | Roger Sayle <roger@nextmovesoftware.com> | 2022-02-22 12:32:22 +0000 |
| commit | 2ef0e75d0bbc80bc06a0a39135e3564f907e39c8 (patch) | |
| tree | 1ceacdf57c7c09f000456ec8aa17f0669a7a71b8 /gcc/fold-const.h | |
| parent | 2f59f067610f22c3f2ec9b1516e24b85836676ed (diff) | |
| download | gcc-2ef0e75d0bbc80bc06a0a39135e3564f907e39c8.zip gcc-2ef0e75d0bbc80bc06a0a39135e3564f907e39c8.tar.gz gcc-2ef0e75d0bbc80bc06a0a39135e3564f907e39c8.tar.bz2 | |
Implement constant-folding simplifications of reductions.
This patch addresses a code quality regression in GCC 12 by implementing
some constant folding/simplification transformations for REDUC_PLUS_EXPR
in match.pd. The motivating example is gcc.dg/vect/pr89440.c which with
-O2 -ffast-math (with vectorization now enabled) gets optimized to:
float f (float x)
{
vector(4) float vect_x_14.11;
vector(4) float _2;
float _32;
_2 = {x_9(D), 0.0, 0.0, 0.0};
vect_x_14.11_29 = _2 + { 1.0e+1, 2.6e+1, 4.2e+1, 5.8e+1 };
_32 = .REDUC_PLUS (vect_x_14.11_29); [tail call]
return _32;
}
With these proposed new transformations, we can simplify the
above code even further.
float f (float x)
{
float _32;
_32 = x_9(D) + 1.36e+2;
return _32;
}
[which happens to match what we'd produce with -fno-tree-vectorize,
and with GCC 11].
2022-02-22 Roger Sayle <roger@nextmovesoftware.com>
Richard Biener <rguenther@suse.de>
gcc/ChangeLog
* fold-const.cc (ctor_single_nonzero_element): New function to
return the single non-zero element of a (vector) constructor.
* fold-const.h (ctor_single_nonzero_element): Prototype here.
* match.pd (reduc (constructor@0)): Simplify reductions of a
constructor containing a single non-zero element.
(reduc (@0 op VECTOR_CST) -> (reduc @0) op CONST): Simplify
reductions of vector operations of the same operator with
constant vector operands.
gcc/testsuite/ChangeLog
* gcc.dg/fold-reduc-1.c: New test case.
Diffstat (limited to 'gcc/fold-const.h')
| -rw-r--r-- | gcc/fold-const.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/gcc/fold-const.h b/gcc/fold-const.h index 926c775..a4ff554 100644 --- a/gcc/fold-const.h +++ b/gcc/fold-const.h @@ -225,6 +225,7 @@ extern const char *c_getstr (tree); extern wide_int tree_nonzero_bits (const_tree); extern int address_compare (tree_code, tree, tree, tree, tree &, tree &, poly_int64 &, poly_int64 &, bool); +extern tree ctor_single_nonzero_element (const_tree); /* Return OFF converted to a pointer offset type suitable as offset for POINTER_PLUS_EXPR. Use location LOC for this conversion. */ |