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| author | mlugg <mlugg@mlugg.co.uk> | 2025-09-27 11:18:33 +0100 |
|---|---|---|
| committer | Jacob Young <jacobly0@users.noreply.github.com> | 2025-09-27 18:30:52 -0400 |
| commit | 611c38e6daffc18bc044ebb1e20d161b4ef757f2 (patch) | |
| tree | f825f464e0bfcfdaf3d4894a7006af8edfb62dfd /src/codegen/x86_64/CodeGen.zig | |
| parent | 77fca1652fce295fe0dd7c97432c23b0c4483724 (diff) | |
| download | zig-611c38e6daffc18bc044ebb1e20d161b4ef757f2.tar.gz zig-611c38e6daffc18bc044ebb1e20d161b4ef757f2.zip | |
x86_64: fix unencodable `rem` lowerings
The memory operand might use one of the extended GPRs R8 through R15 and
hence require a REX prefix, but having a REX prefix makes the high-byte
register AH unencodeable as the src operand. This latent bug was exposed
by this branch, presumably because `select` now happens to be putting
something in an extended GPR instead of a legacy GPR.
In theory this could be fixed with minimal cost by introducing a way to
communicate to `select` that neither the destination memory nor the
other temporary can be in an extended GPR. However, I just went for the
simple solution which comes at a cost of one trivial instruction: copy
the remainder from AH to AL, and *then* copy AL to the destination.
Diffstat (limited to 'src/codegen/x86_64/CodeGen.zig')
| -rw-r--r-- | src/codegen/x86_64/CodeGen.zig | 12 |
1 files changed, 8 insertions, 4 deletions
diff --git a/src/codegen/x86_64/CodeGen.zig b/src/codegen/x86_64/CodeGen.zig index 9eb33931b3..ffc09f2cb7 100644 --- a/src/codegen/x86_64/CodeGen.zig +++ b/src/codegen/x86_64/CodeGen.zig @@ -37912,7 +37912,8 @@ fn genBody(cg: *CodeGen, body: []const Air.Inst.Index) InnerError!void { .{ ._, ._, .mov, .tmp0p, .sa(.src0, .sub_unaligned_size), ._, ._ }, .{ .@"0:", ._, .movsx, .tmp1d, .memia(.src0b, .tmp0, .add_unaligned_size), ._, ._ }, .{ ._, .i_, .div, .memia(.src1b, .tmp0, .add_unaligned_size), ._, ._, ._ }, - .{ ._, ._, .mov, .memia(.dst0b, .tmp0, .add_unaligned_size), .tmp1h, ._, ._ }, + .{ ._, ._, .movsx, .tmp1d, .tmp1h, ._, ._ }, + .{ ._, ._, .mov, .memia(.dst0b, .tmp0, .add_unaligned_size), .tmp1l, ._, ._ }, .{ ._, ._, .add, .tmp0p, .si(1), ._, ._ }, .{ ._, ._nc, .j, .@"0b", ._, ._, ._ }, } }, @@ -37944,7 +37945,8 @@ fn genBody(cg: *CodeGen, body: []const Air.Inst.Index) InnerError!void { .{ ._, ._, .mov, .tmp0p, .sa(.src0, .sub_unaligned_size), ._, ._ }, .{ .@"0:", ._, .movsx, .tmp1d, .memia(.src0b, .tmp0, .add_unaligned_size), ._, ._ }, .{ ._, .i_, .div, .memia(.src1b, .tmp0, .add_unaligned_size), ._, ._, ._ }, - .{ ._, ._, .mov, .memia(.dst0b, .tmp0, .add_unaligned_size), .tmp1h, ._, ._ }, + .{ ._, ._, .movsx, .tmp1d, .tmp1h, ._, ._ }, + .{ ._, ._, .mov, .memia(.dst0b, .tmp0, .add_unaligned_size), .tmp1l, ._, ._ }, .{ ._, ._c, .in, .tmp0p, ._, ._, ._ }, .{ ._, ._nz, .j, .@"0b", ._, ._, ._ }, } }, @@ -37977,7 +37979,8 @@ fn genBody(cg: *CodeGen, body: []const Air.Inst.Index) InnerError!void { .{ ._, ._, .mov, .tmp0p, .sa(.src0, .sub_unaligned_size), ._, ._ }, .{ .@"0:", ._, .movzx, .tmp1d, .memia(.src0b, .tmp0, .add_unaligned_size), ._, ._ }, .{ ._, ._, .div, .memia(.src1b, .tmp0, .add_unaligned_size), ._, ._, ._ }, - .{ ._, ._, .mov, .memia(.dst0b, .tmp0, .add_unaligned_size), .tmp1h, ._, ._ }, + .{ ._, ._, .movzx, .tmp1d, .tmp1h, ._, ._ }, + .{ ._, ._, .mov, .memia(.dst0b, .tmp0, .add_unaligned_size), .tmp1l, ._, ._ }, .{ ._, ._, .add, .tmp0p, .si(1), ._, ._ }, .{ ._, ._nc, .j, .@"0b", ._, ._, ._ }, } }, @@ -38009,7 +38012,8 @@ fn genBody(cg: *CodeGen, body: []const Air.Inst.Index) InnerError!void { .{ ._, ._, .mov, .tmp0p, .sa(.src0, .sub_unaligned_size), ._, ._ }, .{ .@"0:", ._, .movzx, .tmp1d, .memia(.src0b, .tmp0, .add_unaligned_size), ._, ._ }, .{ ._, ._, .div, .memia(.src1b, .tmp0, .add_unaligned_size), ._, ._, ._ }, - .{ ._, ._, .mov, .memia(.dst0b, .tmp0, .add_unaligned_size), .tmp1h, ._, ._ }, + .{ ._, ._, .movzx, .tmp1d, .tmp1h, ._, ._ }, + .{ ._, ._, .mov, .memia(.dst0b, .tmp0, .add_unaligned_size), .tmp1l, ._, ._ }, .{ ._, ._c, .in, .tmp0p, ._, ._, ._ }, .{ ._, ._nz, .j, .@"0b", ._, ._, ._ }, } }, |