spirv backend: do not generate a load for ignored expressions

Fixes spirv-val failing on loads of dynamic arrays.

Bug: chromium:1249602
Change-Id: Ic15af9f9ef2beb45bc732e4e45f023651544a1c7
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/64400
Reviewed-by: Ben Clayton <bclayton@google.com>
Kokoro: Antonio Maiorano <amaiorano@google.com>
Commit-Queue: Antonio Maiorano <amaiorano@google.com>

test/var/initialization/function/array.wgsl.expected.spvasm

@@ -1,7 +1,7 @@
 ; SPIR-V
 ; Version: 1.3
 ; Generator: Google Tint Compiler; 0
-; Bound: 14
+; Bound: 13
 ; Schema: 0
                OpCapability Shader
                OpMemoryModel Logical GLSL450
@@ -21,6 +21,5 @@
        %main = OpFunction %void None %1
           %4 = OpLabel
           %v = OpVariable %_ptr_Function__arr_int_uint_3 Function %11
-         %13 = OpLoad %_arr_int_uint_3 %v
                OpReturn
                OpFunctionEnd

test/var/initialization/function/matrix.wgsl.expected.spvasm

@@ -1,7 +1,7 @@
 ; SPIR-V
 ; Version: 1.3
 ; Generator: Google Tint Compiler; 0
-; Bound: 13
+; Bound: 12
 ; Schema: 0
                OpCapability Shader
                OpMemoryModel Logical GLSL450
@@ -19,6 +19,5 @@
        %main = OpFunction %void None %1
           %4 = OpLabel
           %v = OpVariable %_ptr_Function_mat2v3float Function %10
-         %12 = OpLoad %mat2v3float %v
                OpReturn
                OpFunctionEnd

test/var/initialization/function/scalar.wgsl.expected.spvasm

@@ -1,7 +1,7 @@
 ; SPIR-V
 ; Version: 1.3
 ; Generator: Google Tint Compiler; 0
-; Bound: 11
+; Bound: 10
 ; Schema: 0
                OpCapability Shader
                OpMemoryModel Logical GLSL450
@@ -17,6 +17,5 @@
        %main = OpFunction %void None %1
           %4 = OpLabel
           %v = OpVariable %_ptr_Function_int Function %8
-         %10 = OpLoad %int %v
                OpReturn
                OpFunctionEnd

test/var/initialization/function/struct.wgsl.expected.spvasm

@@ -1,7 +1,7 @@
 ; SPIR-V
 ; Version: 1.3
 ; Generator: Google Tint Compiler; 0
-; Bound: 13
+; Bound: 12
 ; Schema: 0
                OpCapability Shader
                OpMemoryModel Logical GLSL450
@@ -24,6 +24,5 @@
        %main = OpFunction %void None %1
           %4 = OpLabel
           %v = OpVariable %_ptr_Function_S Function %10
-         %12 = OpLoad %S %v
                OpReturn
                OpFunctionEnd

test/var/initialization/function/vector.wgsl.expected.spvasm

@@ -1,7 +1,7 @@
 ; SPIR-V
 ; Version: 1.3
 ; Generator: Google Tint Compiler; 0
-; Bound: 12
+; Bound: 11
 ; Schema: 0
                OpCapability Shader
                OpMemoryModel Logical GLSL450
@@ -18,6 +18,5 @@
        %main = OpFunction %void None %1
           %4 = OpLabel
           %v = OpVariable %_ptr_Function_v3int Function %9
-         %11 = OpLoad %v3int %v
                OpReturn
                OpFunctionEnd

test/var/initialization/private/array.wgsl.expected.spvasm

@@ -1,7 +1,7 @@
 ; SPIR-V
 ; Version: 1.3
 ; Generator: Google Tint Compiler; 0
-; Bound: 14
+; Bound: 13
 ; Schema: 0
                OpCapability Shader
                OpMemoryModel Logical GLSL450
@@ -21,6 +21,5 @@
           %8 = OpTypeFunction %void
        %main = OpFunction %void None %8
          %11 = OpLabel
-         %13 = OpLoad %_arr_int_uint_3 %v
                OpReturn
                OpFunctionEnd

test/var/initialization/private/matrix.wgsl.expected.spvasm

@@ -1,7 +1,7 @@
 ; SPIR-V
 ; Version: 1.3
 ; Generator: Google Tint Compiler; 0
-; Bound: 13
+; Bound: 12
 ; Schema: 0
                OpCapability Shader
                OpMemoryModel Logical GLSL450
@@ -19,6 +19,5 @@
           %7 = OpTypeFunction %void
        %main = OpFunction %void None %7
          %10 = OpLabel
-         %12 = OpLoad %mat2v3float %v
                OpReturn
                OpFunctionEnd

test/var/initialization/private/scalar.wgsl.expected.spvasm

@@ -1,7 +1,7 @@
 ; SPIR-V
 ; Version: 1.3
 ; Generator: Google Tint Compiler; 0
-; Bound: 11
+; Bound: 10
 ; Schema: 0
                OpCapability Shader
                OpMemoryModel Logical GLSL450
@@ -17,6 +17,5 @@
           %5 = OpTypeFunction %void
        %main = OpFunction %void None %5
           %8 = OpLabel
-         %10 = OpLoad %int %v
                OpReturn
                OpFunctionEnd

test/var/initialization/private/struct.wgsl.expected.spvasm

@@ -1,7 +1,7 @@
 ; SPIR-V
 ; Version: 1.3
 ; Generator: Google Tint Compiler; 0
-; Bound: 13
+; Bound: 12
 ; Schema: 0
                OpCapability Shader
                OpMemoryModel Logical GLSL450
@@ -24,6 +24,5 @@
           %7 = OpTypeFunction %void
        %main = OpFunction %void None %7
          %10 = OpLabel
-         %12 = OpLoad %S %v
                OpReturn
                OpFunctionEnd

test/var/initialization/private/vector.wgsl.expected.spvasm

@@ -1,7 +1,7 @@
 ; SPIR-V
 ; Version: 1.3
 ; Generator: Google Tint Compiler; 0
-; Bound: 12
+; Bound: 11
 ; Schema: 0
                OpCapability Shader
                OpMemoryModel Logical GLSL450
@@ -18,6 +18,5 @@
           %6 = OpTypeFunction %void
        %main = OpFunction %void None %6
           %9 = OpLabel
-         %11 = OpLoad %v3int %v
                OpReturn
                OpFunctionEnd

test/var/initialization/workgroup/array.wgsl.expected.spvasm

@@ -1,7 +1,7 @@
 ; SPIR-V
 ; Version: 1.3
 ; Generator: Google Tint Compiler; 0
-; Bound: 44
+; Bound: 43
 ; Schema: 0
                OpCapability Shader
                OpMemoryModel Logical GLSL450
@@ -33,7 +33,7 @@
      %uint_1 = OpConstant %uint 1
      %uint_2 = OpConstant %uint 2
    %uint_264 = OpConstant %uint 264
-         %39 = OpTypeFunction %void
+         %38 = OpTypeFunction %void
  %main_inner = OpFunction %void None %9
 %local_invocation_index = OpFunctionParameter %uint
          %13 = OpLabel
@@ -63,12 +63,11 @@
                OpBranch %17
          %18 = OpLabel
                OpControlBarrier %uint_2 %uint_2 %uint_264
-         %38 = OpLoad %_arr_int_uint_3 %v
                OpReturn
                OpFunctionEnd
-       %main = OpFunction %void None %39
-         %41 = OpLabel
-         %43 = OpLoad %uint %local_invocation_index_1
-         %42 = OpFunctionCall %void %main_inner %43
+       %main = OpFunction %void None %38
+         %40 = OpLabel
+         %42 = OpLoad %uint %local_invocation_index_1
+         %41 = OpFunctionCall %void %main_inner %42
                OpReturn
                OpFunctionEnd

test/var/initialization/workgroup/matrix.wgsl.expected.spvasm

@@ -1,7 +1,7 @@
 ; SPIR-V
 ; Version: 1.3
 ; Generator: Google Tint Compiler; 0
-; Bound: 25
+; Bound: 24
 ; Schema: 0
                OpCapability Shader
                OpMemoryModel Logical GLSL450
@@ -26,18 +26,17 @@
          %14 = OpConstantNull %mat2v3float
      %uint_2 = OpConstant %uint 2
    %uint_264 = OpConstant %uint 264
-         %20 = OpTypeFunction %void
+         %19 = OpTypeFunction %void
  %main_inner = OpFunction %void None %9
 %local_invocation_index = OpFunctionParameter %uint
          %13 = OpLabel
                OpStore %v %14
                OpControlBarrier %uint_2 %uint_2 %uint_264
-         %19 = OpLoad %mat2v3float %v
                OpReturn
                OpFunctionEnd
-       %main = OpFunction %void None %20
-         %22 = OpLabel
-         %24 = OpLoad %uint %local_invocation_index_1
-         %23 = OpFunctionCall %void %main_inner %24
+       %main = OpFunction %void None %19
+         %21 = OpLabel
+         %23 = OpLoad %uint %local_invocation_index_1
+         %22 = OpFunctionCall %void %main_inner %23
                OpReturn
                OpFunctionEnd

test/var/initialization/workgroup/scalar.wgsl.expected.spvasm

@@ -1,7 +1,7 @@
 ; SPIR-V
 ; Version: 1.3
 ; Generator: Google Tint Compiler; 0
-; Bound: 23
+; Bound: 22
 ; Schema: 0
                OpCapability Shader
                OpMemoryModel Logical GLSL450
@@ -24,18 +24,17 @@
          %12 = OpConstantNull %int
      %uint_2 = OpConstant %uint 2
    %uint_264 = OpConstant %uint 264
-         %18 = OpTypeFunction %void
+         %17 = OpTypeFunction %void
  %main_inner = OpFunction %void None %7
 %local_invocation_index = OpFunctionParameter %uint
          %11 = OpLabel
                OpStore %v %12
                OpControlBarrier %uint_2 %uint_2 %uint_264
-         %17 = OpLoad %int %v
                OpReturn
                OpFunctionEnd
-       %main = OpFunction %void None %18
-         %20 = OpLabel
-         %22 = OpLoad %uint %local_invocation_index_1
-         %21 = OpFunctionCall %void %main_inner %22
+       %main = OpFunction %void None %17
+         %19 = OpLabel
+         %21 = OpLoad %uint %local_invocation_index_1
+         %20 = OpFunctionCall %void %main_inner %21
                OpReturn
                OpFunctionEnd

test/var/initialization/workgroup/struct.wgsl.expected.spvasm

@@ -1,7 +1,7 @@
 ; SPIR-V
 ; Version: 1.3
 ; Generator: Google Tint Compiler; 0
-; Bound: 25
+; Bound: 24
 ; Schema: 0
                OpCapability Shader
                OpMemoryModel Logical GLSL450
@@ -31,18 +31,17 @@
          %14 = OpConstantNull %S
      %uint_2 = OpConstant %uint 2
    %uint_264 = OpConstant %uint 264
-         %20 = OpTypeFunction %void
+         %19 = OpTypeFunction %void
  %main_inner = OpFunction %void None %9
 %local_invocation_index = OpFunctionParameter %uint
          %13 = OpLabel
                OpStore %v %14
                OpControlBarrier %uint_2 %uint_2 %uint_264
-         %19 = OpLoad %S %v
                OpReturn
                OpFunctionEnd
-       %main = OpFunction %void None %20
-         %22 = OpLabel
-         %24 = OpLoad %uint %local_invocation_index_1
-         %23 = OpFunctionCall %void %main_inner %24
+       %main = OpFunction %void None %19
+         %21 = OpLabel
+         %23 = OpLoad %uint %local_invocation_index_1
+         %22 = OpFunctionCall %void %main_inner %23
                OpReturn
                OpFunctionEnd

test/var/initialization/workgroup/vector.wgsl.expected.spvasm

@@ -1,7 +1,7 @@
 ; SPIR-V
 ; Version: 1.3
 ; Generator: Google Tint Compiler; 0
-; Bound: 24
+; Bound: 23
 ; Schema: 0
                OpCapability Shader
                OpMemoryModel Logical GLSL450
@@ -25,18 +25,17 @@
          %13 = OpConstantNull %v3int
      %uint_2 = OpConstant %uint 2
    %uint_264 = OpConstant %uint 264
-         %19 = OpTypeFunction %void
+         %18 = OpTypeFunction %void
  %main_inner = OpFunction %void None %8
 %local_invocation_index = OpFunctionParameter %uint
          %12 = OpLabel
                OpStore %v %13
                OpControlBarrier %uint_2 %uint_2 %uint_264
-         %18 = OpLoad %v3int %v
                OpReturn
                OpFunctionEnd
-       %main = OpFunction %void None %19
-         %21 = OpLabel
-         %23 = OpLoad %uint %local_invocation_index_1
-         %22 = OpFunctionCall %void %main_inner %23
+       %main = OpFunction %void None %18
+         %20 = OpLabel
+         %22 = OpLoad %uint %local_invocation_index_1
+         %21 = OpFunctionCall %void %main_inner %22
                OpReturn
                OpFunctionEnd