David Neto dffa60ca98 spir-writer: handle break continuing block
The continuing block can exit the loop in very constrained ways:

When a break statement is placed such that it would exit from a loop’s
§ 7.3.8 Continuing Statement, then:

   - The break statement must appear as either:
     - The only statement in the if clause of an if statement that has:
       - no else clause or an empty else clause
       - no elseif clauses
     - The only statement in the else clause of an if statement that has an
       empty if clause and no elseif clauses.
   - That if statement must appear last in the continuing clause.

By design, this allows a lossless round-trip from SPIR-V to WGSL and
back to SPIR-V.  But that requires this special case construct in WGSL
to be translated to an OpBranchConditional with one target being
the loop's megre block (which is where 'break' branches to), and the
other targets the loop header (which is the loop backedge).  That
OpBranchConditional takes the place of the normal case of an
unconditional backedge.

Avoids errors like this:
 continue construct with the continue target X is not
 post dominated by the back-edge block Y

Fixed: 1034
Change-Id: If472a179380b8d77af746a3cd8e279c8a5e56b37
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/59800
Auto-Submit: David Neto <dneto@google.com>
Kokoro: Kokoro <noreply+kokoro@google.com>
Commit-Queue: David Neto <dneto@google.com>
Reviewed-by: Ben Clayton <bclayton@google.com>
2021-07-27 15:12:27 +00:00

171 lines
6.8 KiB
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; SPIR-V
; Version: 1.3
; Generator: Google Tint Compiler; 0
; Bound: 104
; Schema: 0
OpCapability Shader
OpMemoryModel Logical GLSL450
OpEntryPoint Fragment %main "main" %tint_symbol_1
OpExecutionMode %main OriginUpperLeft
OpName %x_GLF_color "x_GLF_color"
OpName %buf0 "buf0"
OpMemberName %buf0 0 "x_GLF_uniform_float_values"
OpName %x_5 "x_5"
OpName %buf1 "buf1"
OpMemberName %buf1 0 "x_GLF_uniform_int_values"
OpName %x_8 "x_8"
OpName %tint_symbol_1 "tint_symbol_1"
OpName %main_1 "main_1"
OpName %a "a"
OpName %main_out "main_out"
OpMemberName %main_out 0 "x_GLF_color_1"
OpName %tint_symbol_2 "tint_symbol_2"
OpName %tint_symbol "tint_symbol"
OpName %main "main"
OpDecorate %buf0 Block
OpMemberDecorate %buf0 0 Offset 0
OpDecorate %_arr_float_uint_2 ArrayStride 16
OpDecorate %x_5 NonWritable
OpDecorate %x_5 DescriptorSet 0
OpDecorate %x_5 Binding 0
OpDecorate %buf1 Block
OpMemberDecorate %buf1 0 Offset 0
OpDecorate %_arr_int_uint_2 ArrayStride 16
OpDecorate %x_8 NonWritable
OpDecorate %x_8 DescriptorSet 0
OpDecorate %x_8 Binding 1
OpDecorate %tint_symbol_1 Location 0
OpMemberDecorate %main_out 0 Offset 0
%float = OpTypeFloat 32
%v4float = OpTypeVector %float 4
%_ptr_Private_v4float = OpTypePointer Private %v4float
%5 = OpConstantNull %v4float
%x_GLF_color = OpVariable %_ptr_Private_v4float Private %5
%uint = OpTypeInt 32 0
%uint_2 = OpConstant %uint 2
%_arr_float_uint_2 = OpTypeArray %float %uint_2
%buf0 = OpTypeStruct %_arr_float_uint_2
%_ptr_Uniform_buf0 = OpTypePointer Uniform %buf0
%x_5 = OpVariable %_ptr_Uniform_buf0 Uniform
%int = OpTypeInt 32 1
%_arr_int_uint_2 = OpTypeArray %int %uint_2
%buf1 = OpTypeStruct %_arr_int_uint_2
%_ptr_Uniform_buf1 = OpTypePointer Uniform %buf1
%x_8 = OpVariable %_ptr_Uniform_buf1 Uniform
%_ptr_Output_v4float = OpTypePointer Output %v4float
%tint_symbol_1 = OpVariable %_ptr_Output_v4float Output %5
%void = OpTypeVoid
%19 = OpTypeFunction %void
%_ptr_Function_float = OpTypePointer Function %float
%25 = OpConstantNull %float
%uint_0 = OpConstant %uint 0
%int_1 = OpConstant %int 1
%_ptr_Uniform_float = OpTypePointer Uniform %float
%int_0 = OpConstant %int 0
%float_0_200000003 = OpConstant %float 0.200000003
%bool = OpTypeBool
%float_0 = OpConstant %float 0
%_ptr_Uniform_int = OpTypePointer Uniform %int
%main_out = OpTypeStruct %v4float
%92 = OpTypeFunction %void %main_out
%main_1 = OpFunction %void None %19
%22 = OpLabel
%a = OpVariable %_ptr_Function_float Function %25
%29 = OpAccessChain %_ptr_Uniform_float %x_5 %uint_0 %int_1
%30 = OpLoad %float %29
%31 = OpCompositeConstruct %v4float %30 %30 %30 %30
OpStore %x_GLF_color %31
%33 = OpAccessChain %_ptr_Uniform_float %x_5 %uint_0 %int_0
%34 = OpLoad %float %33
OpStore %a %34
OpBranch %35
%35 = OpLabel
OpLoopMerge %36 %37 None
OpBranch %38
%38 = OpLabel
%39 = OpAccessChain %_ptr_Uniform_float %x_5 %uint_0 %int_0
%40 = OpLoad %float %39
%41 = OpAccessChain %_ptr_Uniform_float %x_5 %uint_0 %int_0
%42 = OpLoad %float %41
%44 = OpFDiv %float %40 %float_0_200000003
%45 = OpFOrdLessThan %bool %44 %42
OpSelectionMerge %47 None
OpBranchConditional %45 %48 %47
%48 = OpLabel
OpReturn
%47 = OpLabel
%49 = OpAccessChain %_ptr_Uniform_float %x_5 %uint_0 %int_0
%50 = OpLoad %float %49
%51 = OpAccessChain %_ptr_Uniform_float %x_5 %uint_0 %int_0
%52 = OpLoad %float %51
%53 = OpFDiv %float %50 %float_0_200000003
%54 = OpFOrdLessThan %bool %53 %52
OpSelectionMerge %55 None
OpBranchConditional %54 %56 %55
%56 = OpLabel
OpReturn
%55 = OpLabel
%57 = OpAccessChain %_ptr_Uniform_float %x_5 %uint_0 %int_0
%58 = OpLoad %float %57
%59 = OpAccessChain %_ptr_Uniform_float %x_5 %uint_0 %int_0
%60 = OpLoad %float %59
%61 = OpFDiv %float %58 %float_0_200000003
%62 = OpFOrdLessThan %bool %61 %60
OpSelectionMerge %63 None
OpBranchConditional %62 %64 %63
%64 = OpLabel
OpReturn
%63 = OpLabel
%65 = OpAccessChain %_ptr_Uniform_float %x_5 %uint_0 %int_0
%66 = OpLoad %float %65
%67 = OpAccessChain %_ptr_Uniform_float %x_5 %uint_0 %int_0
%68 = OpLoad %float %67
%69 = OpFDiv %float %66 %float_0_200000003
%70 = OpFOrdLessThan %bool %69 %68
OpSelectionMerge %71 None
OpBranchConditional %70 %72 %73
%72 = OpLabel
OpReturn
%73 = OpLabel
OpStore %a %float_0
OpBranch %71
%71 = OpLabel
OpBranch %37
%37 = OpLabel
%75 = OpLoad %float %a
%77 = OpFOrdEqual %bool %75 %float_0
%76 = OpLogicalNot %bool %77
OpBranchConditional %76 %35 %36
%36 = OpLabel
%79 = OpAccessChain %_ptr_Uniform_int %x_8 %uint_0 %int_1
%80 = OpLoad %int %79
%81 = OpAccessChain %_ptr_Uniform_int %x_8 %uint_0 %int_0
%82 = OpLoad %int %81
%83 = OpAccessChain %_ptr_Uniform_int %x_8 %uint_0 %int_0
%84 = OpLoad %int %83
%85 = OpAccessChain %_ptr_Uniform_int %x_8 %uint_0 %int_1
%86 = OpLoad %int %85
%87 = OpConvertSToF %float %80
%88 = OpConvertSToF %float %82
%89 = OpConvertSToF %float %84
%90 = OpConvertSToF %float %86
%91 = OpCompositeConstruct %v4float %87 %88 %89 %90
OpStore %x_GLF_color %91
OpReturn
OpFunctionEnd
%tint_symbol_2 = OpFunction %void None %92
%tint_symbol = OpFunctionParameter %main_out
%96 = OpLabel
%97 = OpCompositeExtract %v4float %tint_symbol 0
OpStore %tint_symbol_1 %97
OpReturn
OpFunctionEnd
%main = OpFunction %void None %19
%99 = OpLabel
%100 = OpFunctionCall %void %main_1
%102 = OpLoad %v4float %x_GLF_color
%103 = OpCompositeConstruct %main_out %102
%101 = OpFunctionCall %void %tint_symbol_2 %103
OpReturn
OpFunctionEnd