https://github.com/farzonl updated https://github.com/llvm/llvm-project/pull/179836
>From 46f3ad099657bd1e8724c3e03a0cfe4945586624 Mon Sep 17 00:00:00 2001 From: Farzon Lotfi <[email protected]> Date: Wed, 4 Feb 2026 20:48:35 -0500 Subject: [PATCH 1/2] [HLSL] Define CBuffer field alignment for matrix types fixes https://github.com/llvm/llvm-project/issues/179834 Change defines Matrix alignment as buffer row length (16). Same as arrays and structs. Change also adds tests for matrix, matrix in structs, & arrays. --- clang/lib/Sema/SemaHLSL.cpp | 4 +- .../resources/cbuffer_matrix_align.hlsl | 71 +++++++++++++++++++ 2 files changed, 73 insertions(+), 2 deletions(-) create mode 100644 clang/test/CodeGenHLSL/resources/cbuffer_matrix_align.hlsl diff --git a/clang/lib/Sema/SemaHLSL.cpp b/clang/lib/Sema/SemaHLSL.cpp index 4823bb4265789..802a1bdbccfdd 100644 --- a/clang/lib/Sema/SemaHLSL.cpp +++ b/clang/lib/Sema/SemaHLSL.cpp @@ -218,8 +218,8 @@ Decl *SemaHLSL::ActOnStartBuffer(Scope *BufferScope, bool CBuffer, static unsigned calculateLegacyCbufferFieldAlign(const ASTContext &Context, QualType T) { - // Arrays and Structs are always aligned to new buffer rows - if (T->isArrayType() || T->isStructureType()) + // Arrays, Matrices, and Structs are always aligned to new buffer rows + if (T->isArrayType() || T->isStructureType() || T->isConstantMatrixType()) return 16; // Vectors are aligned to the type they contain diff --git a/clang/test/CodeGenHLSL/resources/cbuffer_matrix_align.hlsl b/clang/test/CodeGenHLSL/resources/cbuffer_matrix_align.hlsl new file mode 100644 index 0000000000000..ff4ce0f104f44 --- /dev/null +++ b/clang/test/CodeGenHLSL/resources/cbuffer_matrix_align.hlsl @@ -0,0 +1,71 @@ +// RUN: %clang_cc1 -std=hlsl202x -finclude-default-header -x hlsl -triple dxil-pc-shadermodel6.3-library %s -fnative-half-type -fsyntax-only -verify -verify-ignore-unexpected=warning + +cbuffer MatArr0Pass { + float2x4 A0p[2] : packoffset(c0.x); + float a0tail : packoffset(c4.x); +} + +cbuffer MatArr0Fail { + float2x4 A0f[2] : packoffset(c0.x); + float a0bad : packoffset(c1.w); + // expected-error@-1 {{packoffset overlap between 'a0bad', 'A0f'}} +} + +// Struct containing a matrix. + +struct MS0 { + float2x4 M; + float2 V; +}; + +cbuffer MatStruct0Pass { + MS0 s0p : packoffset(c0.x); + float s0tail: packoffset(c5.x); +} + +cbuffer MatStruct0Fail { + MS0 s0f : packoffset(c0.x); + float s0bad : packoffset(c0.y); + // expected-error@-1 {{packoffset overlap between 's0bad', 's0f'}} +} + +// Nested struct containing a matrix. +struct Inner0 { + float2x4 M; + float F; +}; + +struct Outer0 { + float2 Head; + Inner0 I; + float2 Tail; +}; + +cbuffer MatNested0Pass { + Outer0 o0p : packoffset(c0.x); + float o0tail: packoffset(c8.x); +} + +cbuffer MatNested0Fail { + Outer0 o0f : packoffset(c0.x); + float o0bad: packoffset(c3.y); + // expected-error@-1 {{packoffset overlap between 'o0bad', 'o0f'}} +} + +// Array-of-struct where struct contains a matrix. + +struct AMS0 { + float2x4 M; + float2 V; +}; + +cbuffer MatArrStruct0Pass { + AMS0 as0p[2] : packoffset(c0.x); + float as0tail : packoffset(c10.x); +} + +cbuffer MatArrStruct0Fail { + AMS0 as0f[2] : packoffset(c0.x); + float as0bad : packoffset(c4.z); + // expected-error@-1 {{packoffset overlap between 'as0bad', 'as0f'}} +} >From 03f2ea7bc156cce2c29b61662c39e589cd5591cc Mon Sep 17 00:00:00 2001 From: Farzon Lotfi <[email protected]> Date: Wed, 18 Feb 2026 11:51:04 -0500 Subject: [PATCH 2/2] update tests to have tighter boundaries --- .../resources/cbuffer_matrix_align.hlsl | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-) diff --git a/clang/test/CodeGenHLSL/resources/cbuffer_matrix_align.hlsl b/clang/test/CodeGenHLSL/resources/cbuffer_matrix_align.hlsl index ff4ce0f104f44..70b2732372691 100644 --- a/clang/test/CodeGenHLSL/resources/cbuffer_matrix_align.hlsl +++ b/clang/test/CodeGenHLSL/resources/cbuffer_matrix_align.hlsl @@ -7,7 +7,7 @@ cbuffer MatArr0Pass { cbuffer MatArr0Fail { float2x4 A0f[2] : packoffset(c0.x); - float a0bad : packoffset(c1.w); + float a0bad : packoffset(c3.z); // expected-error@-1 {{packoffset overlap between 'a0bad', 'A0f'}} } @@ -20,12 +20,12 @@ struct MS0 { cbuffer MatStruct0Pass { MS0 s0p : packoffset(c0.x); - float s0tail: packoffset(c5.x); + float s0tail: packoffset(c2.z); } cbuffer MatStruct0Fail { MS0 s0f : packoffset(c0.x); - float s0bad : packoffset(c0.y); + float s0bad : packoffset(c2.y); // expected-error@-1 {{packoffset overlap between 's0bad', 's0f'}} } @@ -43,12 +43,12 @@ struct Outer0 { cbuffer MatNested0Pass { Outer0 o0p : packoffset(c0.x); - float o0tail: packoffset(c8.x); + float o0tail: packoffset(c4.x); } cbuffer MatNested0Fail { Outer0 o0f : packoffset(c0.x); - float o0bad: packoffset(c3.y); + float o0bad: packoffset(c3.z); // expected-error@-1 {{packoffset overlap between 'o0bad', 'o0f'}} } @@ -61,11 +61,11 @@ struct AMS0 { cbuffer MatArrStruct0Pass { AMS0 as0p[2] : packoffset(c0.x); - float as0tail : packoffset(c10.x); + float as0tail : packoffset(c5.z); } cbuffer MatArrStruct0Fail { AMS0 as0f[2] : packoffset(c0.x); - float as0bad : packoffset(c4.z); + float as0bad : packoffset(c5.y); // expected-error@-1 {{packoffset overlap between 'as0bad', 'as0f'}} } _______________________________________________ cfe-commits mailing list [email protected] https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
