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| author | Richard Henderson <richard.henderson@linaro.org> | 2025-01-14 23:08:24 -0800 |
|---|---|---|
| committer | Richard Henderson <richard.henderson@linaro.org> | 2025-04-28 13:40:17 -0700 |
| commit | e2f5ee36afb3b5306c99f40044534ae7d2580114 (patch) | |
| tree | bbed6a6e8bb0c06d934aee0422248c29b2404bf3 | |
| parent | aeb3514bd06b278dd026c90e8f71ca5b32762ab9 (diff) | |
| download | qemu-e2f5ee36afb3b5306c99f40044534ae7d2580114.zip qemu-e2f5ee36afb3b5306c99f40044534ae7d2580114.tar.gz qemu-e2f5ee36afb3b5306c99f40044534ae7d2580114.tar.bz2 | |
tcg/optimize: With two const operands, prefer 0 in arg1
For most binary operands, two const operands fold.
However, the add/sub carry opcodes have a third input.
Prefer "reg, zero, const" since many risc hosts have a
zero register that can fit a "reg, reg, const" insn format.
Reviewed-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
| -rw-r--r-- | tcg/optimize.c | 18 |
1 files changed, 12 insertions, 6 deletions
diff --git a/tcg/optimize.c b/tcg/optimize.c index cfcd0ab..95ec3b4 100644 --- a/tcg/optimize.c +++ b/tcg/optimize.c @@ -737,12 +737,18 @@ static int do_constant_folding_cond(TCGType type, TCGArg x, #define NO_DEST temp_arg(NULL) +static int pref_commutative(TempOptInfo *ti) +{ + /* Slight preference for non-zero constants second. */ + return !ti_is_const(ti) ? 0 : ti_const_val(ti) ? 3 : 2; +} + static bool swap_commutative(TCGArg dest, TCGArg *p1, TCGArg *p2) { TCGArg a1 = *p1, a2 = *p2; int sum = 0; - sum += arg_is_const(a1); - sum -= arg_is_const(a2); + sum += pref_commutative(arg_info(a1)); + sum -= pref_commutative(arg_info(a2)); /* Prefer the constant in second argument, and then the form op a, a, b, which is better handled on non-RISC hosts. */ @@ -757,10 +763,10 @@ static bool swap_commutative(TCGArg dest, TCGArg *p1, TCGArg *p2) static bool swap_commutative2(TCGArg *p1, TCGArg *p2) { int sum = 0; - sum += arg_is_const(p1[0]); - sum += arg_is_const(p1[1]); - sum -= arg_is_const(p2[0]); - sum -= arg_is_const(p2[1]); + sum += pref_commutative(arg_info(p1[0])); + sum += pref_commutative(arg_info(p1[1])); + sum -= pref_commutative(arg_info(p2[0])); + sum -= pref_commutative(arg_info(p2[1])); if (sum > 0) { TCGArg t; t = p1[0], p1[0] = p2[0], p2[0] = t; |