Mesa (master): aco: ensure to not extract more components than have been fetched

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Module: Mesa
Branch: master
Commit: bd75e9923302a3d389469b7b233968576a46f4de
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=bd75e9923302a3d389469b7b233968576a46f4de

Author: Daniel Schürmann <daniel at schuermann.dev>
Date:   Wed Jul 22 16:41:41 2020 +0200

aco: ensure to not extract more components than have been fetched

Fixes: 7015d2c249e1f7814bf5681ccd049e49e4d6495c ('aco: fix scratch loads which cross element_size boundaries')
Cc: 20.1 <mesa-stable at lists.freedesktop.org>
Reviewed-by: Rhys Perry <pendingchaos02 at gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6024>

---

 src/amd/compiler/aco_instruction_selection.cpp | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/src/amd/compiler/aco_instruction_selection.cpp b/src/amd/compiler/aco_instruction_selection.cpp
index 0bc0a5c5433..1d7aae1be2e 100644
--- a/src/amd/compiler/aco_instruction_selection.cpp
+++ b/src/amd/compiler/aco_instruction_selection.cpp
@@ -472,7 +472,7 @@ void byte_align_vector(isel_context *ctx, Temp vec, Operand offset, Temp dst, un
       offset = Operand(0u);
    }
 
-   unsigned num_components = dst.bytes() / component_size;
+   unsigned num_components = vec.bytes() / component_size;
    if (vec.regClass() == dst.regClass()) {
       assert(offset.constantValue() == 0);
       bld.copy(Definition(dst), vec);
@@ -480,17 +480,18 @@ void byte_align_vector(isel_context *ctx, Temp vec, Operand offset, Temp dst, un
       return;
    }
 
-   emit_split_vector(ctx, vec, vec.bytes() / component_size);
+   emit_split_vector(ctx, vec, num_components);
    std::array<Temp, NIR_MAX_VEC_COMPONENTS> elems;
    RegClass rc = RegClass(RegType::vgpr, component_size).as_subdword();
 
    assert(offset.constantValue() % component_size == 0);
    unsigned skip = offset.constantValue() / component_size;
-   for (unsigned i = 0; i < num_components; i++)
-      elems[i] = emit_extract_vector(ctx, vec, i + skip, rc);
+   for (unsigned i = skip; i < num_components; i++)
+      elems[i - skip] = emit_extract_vector(ctx, vec, i, rc);
 
    /* if dst is vgpr - split the src and create a shrunk version according to the mask. */
    if (dst.type() == RegType::vgpr) {
+      num_components = dst.bytes() / component_size;
       aco_ptr<Pseudo_instruction> create_vec{create_instruction<Pseudo_instruction>(aco_opcode::p_create_vector, Format::PSEUDO, num_components, 1)};
       for (unsigned i = 0; i < num_components; i++)
          create_vec->operands[i] = Operand(elems[i]);