writer/hlsl: Simplify UBO accesses for static indexing

Use the new semantic constant value information to significantly reduce the complex indexing logic emitted for UBO accesses.
This will dramatically reduce the number of `for` loops that are decayed to `while` loops.

Change-Id: I1b0adb5edde2b4ed39c6beafc2e28106b86e0edd
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/57701
Kokoro: Kokoro <noreply+kokoro@google.com>
Reviewed-by: James Price <jrprice@google.com>

test/buffer/uniform/static_index/read.wgsl

@@ -0,0 +1,37 @@
+struct Inner {
+    x : i32;
+};
+
+[[block]]
+struct S {
+    a : vec3<i32>;
+    b : i32;
+    c : vec3<u32>;
+    d : u32;
+    e : vec3<f32>;
+    f : f32;
+    g : vec2<i32>;
+    h : vec2<i32>;
+    i : mat2x3<f32>;
+    j : mat3x2<f32>;
+    [[align(16)]] k : Inner;
+    [[align(16)]] l : [[stride(16)]] array<Inner, 4>;
+};
+
+[[binding(0), group(0)]] var<uniform> s : S;
+
+[[stage(compute), workgroup_size(1)]]
+fn main() {
+    let a = s.a;
+    let b = s.b;
+    let c = s.c;
+    let d = s.d;
+    let e = s.e;
+    let f = s.f;
+    let g = s.g;
+    let h = s.h;
+    let i = s.i;
+    let j = s.j;
+    let k = s.k;
+    let l = s.l;
+}

test/buffer/uniform/static_index/read.wgsl.expected.hlsl

@@ -0,0 +1,55 @@
+struct Inner {
+  int x;
+};
+struct tint_padded_array_element {
+  Inner el;
+};
+
+float2x3 tint_symbol_7(uint4 buffer[13], uint offset) {
+  const uint scalar_offset = ((offset + 0u)) / 4;
+  const uint scalar_offset_1 = ((offset + 16u)) / 4;
+  return float2x3(asfloat(buffer[scalar_offset / 4].xyz), asfloat(buffer[scalar_offset_1 / 4].xyz));
+}
+
+float3x2 tint_symbol_9(uint4 buffer[13], uint offset) {
+  const uint scalar_offset_2 = ((offset + 0u)) / 4;
+  uint4 ubo_load = buffer[scalar_offset_2 / 4];
+  const uint scalar_offset_3 = ((offset + 8u)) / 4;
+  uint4 ubo_load_1 = buffer[scalar_offset_3 / 4];
+  const uint scalar_offset_4 = ((offset + 16u)) / 4;
+  uint4 ubo_load_2 = buffer[scalar_offset_4 / 4];
+  return float3x2(asfloat(((scalar_offset_2 & 2) ? ubo_load.zw : ubo_load.xy)), asfloat(((scalar_offset_3 & 2) ? ubo_load_1.zw : ubo_load_1.xy)), asfloat(((scalar_offset_4 & 2) ? ubo_load_2.zw : ubo_load_2.xy)));
+}
+
+Inner tint_symbol_10(uint4 buffer[13], uint offset) {
+  const uint scalar_offset_5 = ((offset + 0u)) / 4;
+  const Inner tint_symbol_12 = {asint(buffer[scalar_offset_5 / 4][scalar_offset_5 % 4])};
+  return tint_symbol_12;
+}
+
+typedef tint_padded_array_element tint_symbol_11_ret[4];
+tint_symbol_11_ret tint_symbol_11(uint4 buffer[13], uint offset) {
+  const tint_padded_array_element tint_symbol_13[4] = {{tint_symbol_10(buffer, (offset + 0u))}, {tint_symbol_10(buffer, (offset + 16u))}, {tint_symbol_10(buffer, (offset + 32u))}, {tint_symbol_10(buffer, (offset + 48u))}};
+  return tint_symbol_13;
+}
+
+cbuffer cbuffer_s : register(b0, space0) {
+  uint4 s[13];
+};
+
+[numthreads(1, 1, 1)]
+void main() {
+  const int3 a = asint(s[0].xyz);
+  const int b = asint(s[0].w);
+  const uint3 c = s[1].xyz;
+  const uint d = s[1].w;
+  const float3 e = asfloat(s[2].xyz);
+  const float f = asfloat(s[2].w);
+  const int2 g = asint(s[3].xy);
+  const int2 h = asint(s[3].zw);
+  const float2x3 i = tint_symbol_7(s, 64u);
+  const float3x2 j = tint_symbol_9(s, 96u);
+  const Inner k = tint_symbol_10(s, 128u);
+  const tint_padded_array_element l[4] = tint_symbol_11(s, 144u);
+  return;
+}

test/buffer/uniform/static_index/read.wgsl.expected.msl

@@ -0,0 +1,46 @@
+#include <metal_stdlib>
+
+using namespace metal;
+struct Inner {
+  /* 0x0000 */ int x;
+};
+struct tint_padded_array_element {
+  /* 0x0000 */ Inner el;
+  /* 0x0004 */ int8_t tint_pad[12];
+};
+struct tint_array_wrapper {
+  /* 0x0000 */ tint_padded_array_element arr[4];
+};
+struct S {
+  /* 0x0000 */ packed_int3 a;
+  /* 0x000c */ int b;
+  /* 0x0010 */ packed_uint3 c;
+  /* 0x001c */ uint d;
+  /* 0x0020 */ packed_float3 e;
+  /* 0x002c */ float f;
+  /* 0x0030 */ packed_int2 g;
+  /* 0x0038 */ packed_int2 h;
+  /* 0x0040 */ float2x3 i;
+  /* 0x0060 */ float3x2 j;
+  /* 0x0078 */ int8_t tint_pad_1[8];
+  /* 0x0080 */ Inner k;
+  /* 0x0084 */ int8_t tint_pad_2[12];
+  /* 0x0090 */ tint_array_wrapper l;
+};
+
+kernel void tint_symbol(constant S& s [[buffer(0)]]) {
+  int3 const a = s.a;
+  int const b = s.b;
+  uint3 const c = s.c;
+  uint const d = s.d;
+  float3 const e = s.e;
+  float const f = s.f;
+  int2 const g = s.g;
+  int2 const h = s.h;
+  float2x3 const i = s.i;
+  float3x2 const j = s.j;
+  Inner const k = s.k;
+  tint_array_wrapper const l = s.l;
+  return;
+}
+

test/buffer/uniform/static_index/read.wgsl.expected.spvasm

@@ -0,0 +1,116 @@
+; SPIR-V
+; Version: 1.3
+; Generator: Google Tint Compiler; 0
+; Bound: 67
+; Schema: 0
+               OpCapability Shader
+               OpMemoryModel Logical GLSL450
+               OpEntryPoint GLCompute %main "main"
+               OpExecutionMode %main LocalSize 1 1 1
+               OpName %S "S"
+               OpMemberName %S 0 "a"
+               OpMemberName %S 1 "b"
+               OpMemberName %S 2 "c"
+               OpMemberName %S 3 "d"
+               OpMemberName %S 4 "e"
+               OpMemberName %S 5 "f"
+               OpMemberName %S 6 "g"
+               OpMemberName %S 7 "h"
+               OpMemberName %S 8 "i"
+               OpMemberName %S 9 "j"
+               OpMemberName %S 10 "k"
+               OpName %Inner "Inner"
+               OpMemberName %Inner 0 "x"
+               OpMemberName %S 11 "l"
+               OpName %s "s"
+               OpName %main "main"
+               OpDecorate %S Block
+               OpMemberDecorate %S 0 Offset 0
+               OpMemberDecorate %S 1 Offset 12
+               OpMemberDecorate %S 2 Offset 16
+               OpMemberDecorate %S 3 Offset 28
+               OpMemberDecorate %S 4 Offset 32
+               OpMemberDecorate %S 5 Offset 44
+               OpMemberDecorate %S 6 Offset 48
+               OpMemberDecorate %S 7 Offset 56
+               OpMemberDecorate %S 8 Offset 64
+               OpMemberDecorate %S 8 ColMajor
+               OpMemberDecorate %S 8 MatrixStride 16
+               OpMemberDecorate %S 9 Offset 96
+               OpMemberDecorate %S 9 ColMajor
+               OpMemberDecorate %S 9 MatrixStride 8
+               OpMemberDecorate %S 10 Offset 128
+               OpMemberDecorate %Inner 0 Offset 0
+               OpMemberDecorate %S 11 Offset 144
+               OpDecorate %_arr_Inner_uint_4 ArrayStride 16
+               OpDecorate %s NonWritable
+               OpDecorate %s Binding 0
+               OpDecorate %s DescriptorSet 0
+        %int = OpTypeInt 32 1
+      %v3int = OpTypeVector %int 3
+       %uint = OpTypeInt 32 0
+     %v3uint = OpTypeVector %uint 3
+      %float = OpTypeFloat 32
+    %v3float = OpTypeVector %float 3
+      %v2int = OpTypeVector %int 2
+%mat2v3float = OpTypeMatrix %v3float 2
+    %v2float = OpTypeVector %float 2
+%mat3v2float = OpTypeMatrix %v2float 3
+      %Inner = OpTypeStruct %int
+     %uint_4 = OpConstant %uint 4
+%_arr_Inner_uint_4 = OpTypeArray %Inner %uint_4
+          %S = OpTypeStruct %v3int %int %v3uint %uint %v3float %float %v2int %v2int %mat2v3float %mat3v2float %Inner %_arr_Inner_uint_4
+%_ptr_Uniform_S = OpTypePointer Uniform %S
+          %s = OpVariable %_ptr_Uniform_S Uniform
+       %void = OpTypeVoid
+         %17 = OpTypeFunction %void
+     %uint_0 = OpConstant %uint 0
+%_ptr_Uniform_v3int = OpTypePointer Uniform %v3int
+     %uint_1 = OpConstant %uint 1
+%_ptr_Uniform_int = OpTypePointer Uniform %int
+     %uint_2 = OpConstant %uint 2
+%_ptr_Uniform_v3uint = OpTypePointer Uniform %v3uint
+     %uint_3 = OpConstant %uint 3
+%_ptr_Uniform_uint = OpTypePointer Uniform %uint
+%_ptr_Uniform_v3float = OpTypePointer Uniform %v3float
+     %uint_5 = OpConstant %uint 5
+%_ptr_Uniform_float = OpTypePointer Uniform %float
+     %uint_6 = OpConstant %uint 6
+%_ptr_Uniform_v2int = OpTypePointer Uniform %v2int
+     %uint_7 = OpConstant %uint 7
+     %uint_8 = OpConstant %uint 8
+%_ptr_Uniform_mat2v3float = OpTypePointer Uniform %mat2v3float
+     %uint_9 = OpConstant %uint 9
+%_ptr_Uniform_mat3v2float = OpTypePointer Uniform %mat3v2float
+    %uint_10 = OpConstant %uint 10
+%_ptr_Uniform_Inner = OpTypePointer Uniform %Inner
+    %uint_11 = OpConstant %uint 11
+%_ptr_Uniform__arr_Inner_uint_4 = OpTypePointer Uniform %_arr_Inner_uint_4
+       %main = OpFunction %void None %17
+         %20 = OpLabel
+         %23 = OpAccessChain %_ptr_Uniform_v3int %s %uint_0
+         %24 = OpLoad %v3int %23
+         %27 = OpAccessChain %_ptr_Uniform_int %s %uint_1
+         %28 = OpLoad %int %27
+         %31 = OpAccessChain %_ptr_Uniform_v3uint %s %uint_2
+         %32 = OpLoad %v3uint %31
+         %35 = OpAccessChain %_ptr_Uniform_uint %s %uint_3
+         %36 = OpLoad %uint %35
+         %38 = OpAccessChain %_ptr_Uniform_v3float %s %uint_4
+         %39 = OpLoad %v3float %38
+         %42 = OpAccessChain %_ptr_Uniform_float %s %uint_5
+         %43 = OpLoad %float %42
+         %46 = OpAccessChain %_ptr_Uniform_v2int %s %uint_6
+         %47 = OpLoad %v2int %46
+         %49 = OpAccessChain %_ptr_Uniform_v2int %s %uint_7
+         %50 = OpLoad %v2int %49
+         %53 = OpAccessChain %_ptr_Uniform_mat2v3float %s %uint_8
+         %54 = OpLoad %mat2v3float %53
+         %57 = OpAccessChain %_ptr_Uniform_mat3v2float %s %uint_9
+         %58 = OpLoad %mat3v2float %57
+         %61 = OpAccessChain %_ptr_Uniform_Inner %s %uint_10
+         %62 = OpLoad %Inner %61
+         %65 = OpAccessChain %_ptr_Uniform__arr_Inner_uint_4 %s %uint_11
+         %66 = OpLoad %_arr_Inner_uint_4 %65
+               OpReturn
+               OpFunctionEnd

test/buffer/uniform/static_index/read.wgsl.expected.wgsl

@@ -0,0 +1,39 @@
+struct Inner {
+  x : i32;
+};
+
+[[block]]
+struct S {
+  a : vec3<i32>;
+  b : i32;
+  c : vec3<u32>;
+  d : u32;
+  e : vec3<f32>;
+  f : f32;
+  g : vec2<i32>;
+  h : vec2<i32>;
+  i : mat2x3<f32>;
+  j : mat3x2<f32>;
+  [[align(16)]]
+  k : Inner;
+  [[align(16)]]
+  l : [[stride(16)]] array<Inner, 4>;
+};
+
+[[binding(0), group(0)]] var<uniform> s : S;
+
+[[stage(compute), workgroup_size(1)]]
+fn main() {
+  let a = s.a;
+  let b = s.b;
+  let c = s.c;
+  let d = s.d;
+  let e = s.e;
+  let f = s.f;
+  let g = s.g;
+  let h = s.h;
+  let i = s.i;
+  let j = s.j;
+  let k = s.k;
+  let l = s.l;
+}