Sema: Fix fnptr alignment safety checks to account for potential ISA tag.

As seen on e.g. Arm/Thumb and MIPS (MIPS16/microMIPS).

Fixes #22888.

1 files changed, 24 insertions, 6 deletions

diff --git a/src/Sema.zig b/src/Sema.zig
index cbfeef6339..7e3ab51a29 100644
--- a/src/Sema.zig
+++ b/src/Sema.zig
@@ -23099,8 +23099,14 @@ fn zirPtrFromInt(sema: *Sema, block: *Block, inst: Zir.Inst.Index) CompileError!
             }
             if (ptr_align.compare(.gt, .@"1")) {
                 const align_bytes_minus_1 = ptr_align.toByteUnits().? - 1;
-                const align_minus_1 = Air.internedToRef((try sema.splat(operand_ty, try pt.intValue(Type.usize, align_bytes_minus_1))).toIntern());
-                const remainder = try block.addBinOp(.bit_and, operand_coerced, align_minus_1);
+                const align_mask = Air.internedToRef((try sema.splat(operand_ty, try pt.intValue(
+                    Type.usize,
+                    if (elem_ty.fnPtrMaskOrNull(zcu)) |mask|
+                        align_bytes_minus_1 & mask
+                    else
+                        align_bytes_minus_1,
+                ))).toIntern());
+                const remainder = try block.addBinOp(.bit_and, operand_coerced, align_mask);
                 const is_aligned = if (is_vector) all_aligned: {
                     const splat_zero_usize = Air.internedToRef((try sema.splat(operand_ty, .zero_usize)).toIntern());
                     const is_aligned = try block.addCmpVector(remainder, splat_zero_usize, .eq);
@@ -23129,8 +23135,14 @@ fn zirPtrFromInt(sema: *Sema, block: *Block, inst: Zir.Inst.Index) CompileError!
             }
             if (ptr_align.compare(.gt, .@"1")) {
                 const align_bytes_minus_1 = ptr_align.toByteUnits().? - 1;
-                const align_minus_1 = Air.internedToRef((try pt.intValue(Type.usize, align_bytes_minus_1)).toIntern());
-                const remainder = try block.addBinOp(.bit_and, elem_coerced, align_minus_1);
+                const align_mask = Air.internedToRef((try pt.intValue(
+                    Type.usize,
+                    if (elem_ty.fnPtrMaskOrNull(zcu)) |mask|
+                        align_bytes_minus_1 & mask
+                    else
+                        align_bytes_minus_1,
+                )).toIntern());
+                const remainder = try block.addBinOp(.bit_and, elem_coerced, align_mask);
                 const is_aligned = try block.addBinOp(.cmp_eq, remainder, .zero_usize);
                 try sema.addSafetyCheck(block, src, is_aligned, .incorrect_alignment);
             }
@@ -23710,13 +23722,19 @@ fn ptrCastFull(
         try Type.fromInterned(dest_info.child).hasRuntimeBitsSema(pt))
     {
         const align_bytes_minus_1 = dest_align.toByteUnits().? - 1;
-        const align_minus_1 = Air.internedToRef((try pt.intValue(Type.usize, align_bytes_minus_1)).toIntern());
+        const align_mask = Air.internedToRef((try pt.intValue(
+            Type.usize,
+            if (Type.fromInterned(dest_info.child).fnPtrMaskOrNull(zcu)) |mask|
+                align_bytes_minus_1 & mask
+            else
+                align_bytes_minus_1,
+        )).toIntern());
         const actual_ptr = if (src_info.flags.size == .slice)
             try sema.analyzeSlicePtr(block, src, ptr, operand_ty)
         else
             ptr;
         const ptr_int = try block.addBitCast(.usize, actual_ptr);
-        const remainder = try block.addBinOp(.bit_and, ptr_int, align_minus_1);
+        const remainder = try block.addBinOp(.bit_and, ptr_int, align_mask);
         const is_aligned = try block.addBinOp(.cmp_eq, remainder, .zero_usize);
         const ok = if (src_info.flags.size == .slice and dest_info.flags.size == .slice) ok: {
             const len = try sema.analyzeSliceLen(block, operand_src, ptr);