| author |  Andrew Kelley <andrew@ziglang.org> 2022-05-04 15:22:41-07:00 |
| committer | Andrew Kelley <andrew@ziglang.org> 2022-05-04 17:34:17-07:00 |
| log | f21c11a7f7fb84db4289a6f735dea012387606d6 |
| tree | 9d744e2487ded968fc2ff7003674fe1fe53fff09 |
| parent | 5b1c0d922c1061706ae1673333fcfb1d8fdd4602 |
stage2: change x86_64 max int alignment from 8 to 16
For x86_64, LLVMABIAlignmentOfType(i128) reports 8. However I think 16
is a better number for two reasons:
1. Better machine code when loading into SIMD register.
2. The C ABI wants 16 for extern structs.3 files changed, 11 insertions(+), 10 deletions(-)
lib
std
src
test
behavior
lib/std/target.zig+6-1
| ... | ... | @@ -1784,7 +1784,6 @@ pub const Target = struct { |
| 1784 | 1784 | .armeb, |
| 1785 | 1785 | .thumb, |
| 1786 | 1786 | .thumbeb, |
| 1787 | .x86_64, | |
| 1788 | 1787 | .hexagon, |
| 1789 | 1788 | .mips, |
| 1790 | 1789 | .mipsel, |
| ... | ... | @@ -1811,6 +1810,12 @@ pub const Target = struct { |
| 1811 | 1810 | .windows => 8, |
| 1812 | 1811 | else => 4, |
| 1813 | 1812 | }, |
| 1813 | ||
| 1814 | // For x86_64, LLVMABIAlignmentOfType(i128) reports 8. However I think 16 | |
| 1815 | // is a better number because of two reasons: | |
| 1816 | // 1. Better machine code when loading into SIMD register. | |
| 1817 | // 2. The C ABI wants 16 for extern structs. | |
| 1818 | .x86_64, | |
| 1814 | 1819 | .aarch64, |
| 1815 | 1820 | .aarch64_be, |
| 1816 | 1821 | .aarch64_32, |
src/target.zig+1-8
| ... | ... | @@ -555,7 +555,7 @@ pub const AtomicPtrAlignmentDiagnostics = struct { |
| 555 | 555 | max_bits: u16 = undefined, |
| 556 | 556 | }; |
| 557 | 557 | |
| 558 | /// If ABI alignment of `ty` is OK for atomic operations, returs 0. | |
| 558 | /// If ABI alignment of `ty` is OK for atomic operations, returns 0. | |
| 559 | 559 | /// Otherwise returns the alignment required on a pointer for the target |
| 560 | 560 | /// to perform atomic operations. |
| 561 | 561 | pub fn atomicPtrAlignment( |
| ... | ... | @@ -645,9 +645,6 @@ pub fn atomicPtrAlignment( |
| 645 | 645 | }; |
| 646 | 646 | return error.FloatTooBig; |
| 647 | 647 | } |
| 648 | if (target.cpu.arch == .x86_64 and bit_count > 64) { | |
| 649 | return 16; | |
| 650 | } | |
| 651 | 648 | return 0; |
| 652 | 649 | }, |
| 653 | 650 | .Bool => return 0, |
| ... | ... | @@ -666,10 +663,6 @@ pub fn atomicPtrAlignment( |
| 666 | 663 | return error.IntTooBig; |
| 667 | 664 | } |
| 668 | 665 | |
| 669 | if (target.cpu.arch == .x86_64 and bit_count > 64) { | |
| 670 | return 16; | |
| 671 | } | |
| 672 | ||
| 673 | 666 | return 0; |
| 674 | 667 | } |
| 675 | 668 |
test/behavior/align.zig+4-1
| ... | ... | @@ -55,6 +55,9 @@ test "alignment of struct with pointer has same alignment as usize" { |
| 55 | 55 | } |
| 56 | 56 | |
| 57 | 57 | test "alignment and size of structs with 128-bit fields" { |
| 58 | if (builtin.zig_backend == .stage2_arm) return error.SkipZigTest; // TODO | |
| 59 | if (builtin.zig_backend == .stage2_aarch64) return error.SkipZigTest; // TODO | |
| 60 | ||
| 58 | 61 | const A = struct { |
| 59 | 62 | x: u128, |
| 60 | 63 | }; |
| ... | ... | @@ -67,7 +70,6 @@ test "alignment and size of structs with 128-bit fields" { |
| 67 | 70 | .armeb, |
| 68 | 71 | .thumb, |
| 69 | 72 | .thumbeb, |
| 70 | .x86_64, | |
| 71 | 73 | .hexagon, |
| 72 | 74 | .mips, |
| 73 | 75 | .mipsel, |
| ... | ... | @@ -128,6 +130,7 @@ test "alignment and size of structs with 128-bit fields" { |
| 128 | 130 | }, |
| 129 | 131 | }, |
| 130 | 132 | |
| 133 | .x86_64, | |
| 131 | 134 | .aarch64, |
| 132 | 135 | .aarch64_be, |
| 133 | 136 | .aarch64_32, |