Mesa (staging/21.1): radv,ac/llvm: use a dword alignment for descriptor loads

[GitLab Mirror]

Module: Mesa
Branch: staging/21.1
Commit: 42559426547128d96093e00213e174142b75f1bd
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=42559426547128d96093e00213e174142b75f1bd

Author: Rhys Perry <pendingchaos02 at gmail.com>
Date:   Fri Apr 30 11:39:12 2021 +0100

radv,ac/llvm: use a dword alignment for descriptor loads

RADV doesn't try to keep anything 16 or 32 byte aligned. RADV also seems
to create better code for some reason.

fossil-db (Sienna Cichlid):
Totals from 37693 (30.93% of 121873) affected shaders:
SGPRs: 1762792 -> 1785504 (+1.29%); split: -1.01%, +2.30%
VGPRs: 1761032 -> 1760808 (-0.01%); split: -0.09%, +0.07%
SpillSGPRs: 55793 -> 56011 (+0.39%); split: -3.49%, +3.88%
SpillVGPRs: 16766 -> 16387 (-2.26%); split: -3.99%, +1.73%
CodeSize: 82902228 -> 82781608 (-0.15%); split: -0.29%, +0.14%
Scratch: 3024896 -> 2987008 (-1.25%); split: -3.08%, +1.83%
MaxWaves: 919794 -> 920302 (+0.06%); split: +0.09%, -0.03%

shader-db (Sienna Cichlid):
Totals from affected shaders:
SGPRS: 3976 -> 3976 (0.00 %)
VGPRS: 3392 -> 3392 (0.00 %)
Spilled SGPRs: 0 -> 0 (0.00 %)
Spilled VGPRs: 0 -> 0 (0.00 %)
Private memory VGPRs: 0 -> 0 (0.00 %)
Scratch size: 0 -> 0 (0.00 %) dwords per thread
Code Size: 178792 -> 178980 (0.11 %) bytes
Max Waves: 1389 -> 1389 (0.00 %)

Signed-off-by: Rhys Perry <pendingchaos02 at gmail.com>
Reviewed-by: Marek Olšák <marek.olsak at amd.com>
Cc: mesa-stable
Closes: https://gitlab.freedesktop.org/mesa/mesa/-/issues/4715
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/10543>
(cherry picked from commit d918a59d15fdba02f57e40039acc5baf6fef67e7)

---

 .pick_status.json                 | 2 +-
 src/amd/llvm/ac_llvm_build.c      | 3 ++-
 src/amd/vulkan/radv_nir_to_llvm.c | 3 +++
 3 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/.pick_status.json b/.pick_status.json
index fa6eb7ae3bb..b3040a3a94a 100644
--- a/.pick_status.json
+++ b/.pick_status.json
@@ -220,7 +220,7 @@
         "description": "radv,ac/llvm: use a dword alignment for descriptor loads",
         "nominated": true,
         "nomination_type": 0,
-        "resolution": 0,
+        "resolution": 1,
         "master_sha": null,
         "because_sha": null
     },
diff --git a/src/amd/llvm/ac_llvm_build.c b/src/amd/llvm/ac_llvm_build.c
index 1bc0ef6086d..6106c47f6e4 100644
--- a/src/amd/llvm/ac_llvm_build.c
+++ b/src/amd/llvm/ac_llvm_build.c
@@ -1066,6 +1066,7 @@ static LLVMValueRef ac_build_load_custom(struct ac_llvm_context *ctx, LLVMValueR
    result = LLVMBuildLoad(ctx->builder, pointer, "");
    if (invariant)
       LLVMSetMetadata(result, ctx->invariant_load_md_kind, ctx->empty_md);
+   LLVMSetAlignment(result, 4);
    return result;
 }
 
@@ -4761,7 +4762,7 @@ LLVMValueRef ac_build_main(const struct ac_shader_args *args, struct ac_llvm_con
       if (LLVMGetTypeKind(LLVMTypeOf(P)) == LLVMPointerTypeKind) {
          ac_add_function_attr(ctx->context, main_function, i + 1, AC_FUNC_ATTR_NOALIAS);
          ac_add_attr_dereferenceable(P, UINT64_MAX);
-         ac_add_attr_alignment(P, 32);
+         ac_add_attr_alignment(P, 4);
       }
    }
 
diff --git a/src/amd/vulkan/radv_nir_to_llvm.c b/src/amd/vulkan/radv_nir_to_llvm.c
index 59e9fee3118..39abac0d207 100644
--- a/src/amd/vulkan/radv_nir_to_llvm.c
+++ b/src/amd/vulkan/radv_nir_to_llvm.c
@@ -122,6 +122,7 @@ load_descriptor_sets(struct radv_shader_context *ctx)
 
          ctx->descriptor_sets[i] =
             ac_build_load_to_sgpr(&ctx->ac, desc_sets, LLVMConstInt(ctx->ac.i32, i, false));
+         LLVMSetAlignment(ctx->descriptor_sets[i], 4);
       }
    } else {
       while (mask) {
@@ -437,6 +438,7 @@ radv_load_ssbo(struct ac_shader_abi *abi, LLVMValueRef buffer_ptr, bool write, b
 
    result = LLVMBuildLoad(ctx->ac.builder, buffer_ptr, "");
    LLVMSetMetadata(result, ctx->ac.invariant_load_md_kind, ctx->ac.empty_md);
+   LLVMSetAlignment(result, 4);
 
    return result;
 }
@@ -481,6 +483,7 @@ radv_load_ubo(struct ac_shader_abi *abi, unsigned desc_set, unsigned binding, bo
 
    result = LLVMBuildLoad(ctx->ac.builder, buffer_ptr, "");
    LLVMSetMetadata(result, ctx->ac.invariant_load_md_kind, ctx->ac.empty_md);
+   LLVMSetAlignment(result, 4);
 
    return result;
 }