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| author | Joern Rennecke <joern.rennecke@embecosm.com> | 2013-04-10 09:54:25 +0000 |
|---|---|---|
| committer | Joern Rennecke <amylaar@gcc.gnu.org> | 2013-04-10 10:54:25 +0100 |
| commit | ee8a9b7b507013b0431cabd314a245461c3b86b9 (patch) | |
| tree | 1fe05c42b5420c41fb7bc6483e954ffd10927339 /gcc/tree-ssa-math-opts.c | |
| parent | 6957a6f6f90ef5be56e154ee7ce8656ec0248e6f (diff) | |
| download | gcc-ee8a9b7b507013b0431cabd314a245461c3b86b9.zip gcc-ee8a9b7b507013b0431cabd314a245461c3b86b9.tar.gz gcc-ee8a9b7b507013b0431cabd314a245461c3b86b9.tar.bz2 | |
re PR tree-optimization/55524 (If fnma exists but not fms, convert_mult_to_fma should prefer to former over the latter.)
gcc:
2013-04-10 Joern Rennecke <joern.rennecke@embecosm.com>
PR tree-optimization/55524
* tree-ssa-math-opts.c
(convert_mult_to_fma): Don't use an fms construct
when we don't have an fms operation, but fnma, and it looks
likely that we'll be able to use the latter.
gcc/testsuite:
2013-04-10 Joern Rennecke <joern.rennecke@embecosm.com>
PR tree-optimization/55524
* gcc.target/epiphany/fnma-1.c: New test.
From-SVN: r197668
Diffstat (limited to 'gcc/tree-ssa-math-opts.c')
| -rw-r--r-- | gcc/tree-ssa-math-opts.c | 18 |
1 files changed, 18 insertions, 0 deletions
diff --git a/gcc/tree-ssa-math-opts.c b/gcc/tree-ssa-math-opts.c index 2140ced..e7e09f6 100644 --- a/gcc/tree-ssa-math-opts.c +++ b/gcc/tree-ssa-math-opts.c @@ -2570,6 +2570,24 @@ convert_mult_to_fma (gimple mul_stmt, tree op1, tree op2) return false; } + /* If the subtrahend (gimple_assign_rhs2 (use_stmt)) is computed + by a MULT_EXPR that we'll visit later, we might be able to + get a more profitable match with fnma. + OTOH, if we don't, a negate / fma pair has likely lower latency + that a mult / subtract pair. */ + if (use_code == MINUS_EXPR && !negate_p + && gimple_assign_rhs1 (use_stmt) == result + && optab_handler (fms_optab, TYPE_MODE (type)) == CODE_FOR_nothing + && optab_handler (fnma_optab, TYPE_MODE (type)) != CODE_FOR_nothing) + { + tree rhs2 = gimple_assign_rhs2 (use_stmt); + gimple stmt2 = SSA_NAME_DEF_STMT (rhs2); + + if (has_single_use (rhs2) + && gimple_assign_rhs_code (stmt2) == MULT_EXPR) + return false; + } + /* We can't handle a * b + a * b. */ if (gimple_assign_rhs1 (use_stmt) == gimple_assign_rhs2 (use_stmt)) return false; |