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sema: add comptime float folding to analyzeArithmetic

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When both operands are comptime-known floats (IP_KEY_FLOAT entries,
including comptime_float and concrete float types), fold the result
at comptime instead of emitting a runtime AIR instruction.

Ported from Sema.zig analyzeArithmetic: resolveValue(casted_lhs/rhs)
path which evaluates comptime values via arith.add/sub/mul.

Handles ADD, SUB, MUL variants (including wrap/sat) for both
comptime_float × comptime_float and concrete float × float. Result
type is the wider of the two float types.

Co-Authored-By: Claude Sonnet 4.6 (1M context) <noreply@anthropic.com>
This commit is contained in:
Motiejus Jakštys
2026-03-07 09:18:22 +00:00
parent fad25d34f9
commit 9487bd9acf
1 changed files with 48 additions and 0 deletions
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48
stage0/sema.c
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@@ -929,6 +929,54 @@ static void addSignedMag128(uint64_t a_lo, uint64_t a_hi, bool a_neg,
// Handles add/sub/mul and their wrap/sat variants.
static AirInstRef analyzeArithmetic(Sema* sema, SemaBlock* block,
AirInstTag air_tag, AirInstRef lhs, AirInstRef rhs) {
// Comptime folding for float operands (comptime_float or concrete float).
// Ported from Sema.zig analyzeArithmetic: resolveValue(casted_lhs/rhs).
if (AIR_REF_IS_IP(lhs) && AIR_REF_IS_IP(rhs)) {
InternPoolKey lk = ipIndexToKey(sema->ip, AIR_REF_TO_IP(lhs));
InternPoolKey rk = ipIndexToKey(sema->ip, AIR_REF_TO_IP(rhs));
if (lk.tag == IP_KEY_FLOAT && rk.tag == IP_KEY_FLOAT) {
double lv = lk.data.float_val.val;
double rv = rk.data.float_val.val;
double result;
switch (air_tag) {
case AIR_INST_ADD:
case AIR_INST_ADD_WRAP:
case AIR_INST_ADD_SAT:
result = lv + rv;
break;
case AIR_INST_SUB:
case AIR_INST_SUB_WRAP:
case AIR_INST_SUB_SAT:
result = lv - rv;
break;
case AIR_INST_MUL:
case AIR_INST_MUL_WRAP:
case AIR_INST_MUL_SAT:
result = lv * rv;
break;
default:
goto after_float_fold;
}
// Result type: pick the wider float (or comptime_float if both
// are).
TypeIndex result_ty
= (lk.data.float_val.ty == IP_INDEX_COMPTIME_FLOAT_TYPE
&& rk.data.float_val.ty == IP_INDEX_COMPTIME_FLOAT_TYPE)
? IP_INDEX_COMPTIME_FLOAT_TYPE
: (floatBits(lk.data.float_val.ty)
>= floatBits(rk.data.float_val.ty)
? lk.data.float_val.ty
: rk.data.float_val.ty);
InternPoolKey key;
memset(&key, 0, sizeof(key));
key.tag = IP_KEY_FLOAT;
key.data.float_val.ty = result_ty;
key.data.float_val.val = result;
return AIR_REF_FROM_IP(ipIntern(sema->ip, key));
}
}
after_float_fold:;
// Comptime folding: if both operands are comptime integers,
// compute the result at comptime (128-bit).
uint64_t lhs_lo, lhs_hi, rhs_lo, rhs_hi;