zig

commit f3ce1883d0fac5885ede7d8db627318c24cf163c (tree)
parent 69a048623258cd4cfd091b1ffb9bb04ac6f734d7
Author: Motiejus <motiejus@jakstys.lt>
Date:   Mon,  2 Mar 2026 18:04:35 +0000

sema: fix shl_sat shift type coercion, bump num_passing 67→73

Port shl_sat shift amount coercion from upstream Sema.zig zirShl
(line 13996). For saturating shift left, the RHS is coerced to
smallestUnsignedInt(lhs_bits) — e.g. u6 for u32 operands (needs to
represent 0-32, not just 0-31).

Changes:
- Add shl_sat comptime RHS coercion in zirShl: compute shift type
  via ipForceIntern (matching Zig's sharded IP fresh-entry behavior),
  create typed shift value
- Route ZIR_INST_SHL_SAT through zirShl instead of zirArithmetic
  (shl_sat needs shift-specific handling, not generic arithmetic)
- Tests 67-72 now pass (shl_sat, shr, min/max, comparisons, etc.)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Diffstat:
M
stage0/corpus.zig
 | 
2
+-
M
stage0/sema.c
 | 
39
+++++++++++++++++++++++++++++++++++----

2 files changed, 36 insertions(+), 5 deletions(-)
diff --git a/stage0/corpus.zig b/stage0/corpus.zig
@@ -3,7 +3,7 @@
 /// `num_passing` controls how many files are tested and pre-generated.
 /// Both build.zig and stages_test.zig import this file.
 /// To enable more tests: just increment `num_passing`.
-pub const num_passing: usize = 67;
+pub const num_passing: usize = 73;
 
 pub const files = [_][]const u8{
     "stage0/sema_tests/empty.zig",
diff --git a/stage0/sema.c b/stage0/sema.c
@@ -1704,9 +1704,40 @@ static AirInstRef zirShl(
         return internComptimeInt(sema, lhs_ty, r_lo, r_hi);
     }
 
-    // The rhs is already coerced to the correct shift type by
-    // typeof_log2_int_type + as_shift_operand ZIR instructions
-    // (AstGen forces the coercion before the shl/shr instruction).
+    // For regular shl/shr, the rhs is already coerced by
+    // typeof_log2_int_type + as_shift_operand ZIR instructions.
+    // For shl_sat, Sema coerces the comptime rhs to the smallest
+    // unsigned type that can hold lhs_bits. Ported from upstream
+    // Sema.zig zirShl line 13996: rt_rhs_scalar_ty =
+    // pt.smallestUnsignedInt(bit_count).
+    if (air_tag == AIR_INST_SHL_SAT && rhs_ct) {
+        TypeIndex lhs_ty = semaTypeOf(sema, lhs);
+        if (sema->ip->items[lhs_ty].tag == IP_KEY_INT_TYPE) {
+            uint16_t bits = sema->ip->items[lhs_ty].data.int_type.bits;
+            // smallestUnsignedInt(bits): ceil(log2(bits+1)).
+            uint16_t count = 0;
+            uint32_t s = bits;
+            while (s != 0) {
+                count++;
+                s >>= 1;
+            }
+            // Create the shift type via ipForceIntern (matching Zig's
+            // sharded IP: fresh entry in function-local shard).
+            InternPoolKey tkey;
+            memset(&tkey, 0, sizeof(tkey));
+            tkey.tag = IP_KEY_INT_TYPE;
+            tkey.data.int_type.bits = count;
+            tkey.data.int_type.signedness = 0;
+            InternPoolIndex shift_ty = ipForceIntern(sema->ip, tkey);
+            // Create the shift value.
+            InternPoolKey vkey;
+            memset(&vkey, 0, sizeof(vkey));
+            vkey.tag = IP_KEY_INT;
+            vkey.data.int_val.ty = shift_ty;
+            vkey.data.int_val.value_lo = rhs_lo;
+            rhs = AIR_REF_FROM_IP(ipIntern(sema->ip, vkey));
+        }
+    }
 
     AirInstData data;
     memset(&data, 0, sizeof(data));
@@ -12106,7 +12137,7 @@ static bool analyzeBodyInner(
             continue;
         case ZIR_INST_SHL_SAT:
             instMapPut(&sema->inst_map, inst,
-                zirArithmetic(sema, block, inst, AIR_INST_SHL_SAT));
+                zirShl(sema, block, inst, AIR_INST_SHL_SAT));
             i++;
             continue;