77702f1704
When we determine that a function only contains a single return
statement and it is at the top level (i.e. not inside any scopes),
there is no need to create a temporary variable and store the
result expression into a variable. Instead, we can directly replace
the function-call expression with the return-statement's expression.
Unlike my previous solution, this does not require variable
declarations to be rewritten. The no-scopes limitation makes it
slightly less effective in theory, but in practice we still get
almost all of the benefit. The no-scope limitation bites us on
structures like
@if (true) {
return x;
} else {
return y;
}
Which will optimize away the if, but leave the scope:
{
return x;
}
However, this is not a big deal; the biggest wins are single-line
helper functions like `guarded_divide` and `unpremul` which retain
the full benefit.
Change-Id: I7fbb725e65db021b9795c04c816819669815578f
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/345167
Commit-Queue: John Stiles <johnstiles@google.com>
Auto-Submit: John Stiles <johnstiles@google.com>
Reviewed-by: Ethan Nicholas <ethannicholas@google.com>
84 lines
2.7 KiB
JavaScript
84 lines
2.7 KiB
JavaScript
OpCapability Shader
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%1 = OpExtInstImport "GLSL.std.450"
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OpMemoryModel Logical GLSL450
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OpEntryPoint Fragment %main "main" %sk_FragColor %sk_Clockwise
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OpExecutionMode %main OriginUpperLeft
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OpName %sk_FragColor "sk_FragColor"
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OpName %sk_Clockwise "sk_Clockwise"
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OpName %main "main"
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OpName %_1_x "_1_x"
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OpName %x "x"
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OpName %_3_x "_3_x"
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OpName %y "y"
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OpDecorate %sk_FragColor RelaxedPrecision
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OpDecorate %sk_FragColor Location 0
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OpDecorate %sk_FragColor Index 0
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OpDecorate %sk_Clockwise RelaxedPrecision
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OpDecorate %sk_Clockwise BuiltIn FrontFacing
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%float = OpTypeFloat 32
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%v4float = OpTypeVector %float 4
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%_ptr_Output_v4float = OpTypePointer Output %v4float
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%sk_FragColor = OpVariable %_ptr_Output_v4float Output
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%bool = OpTypeBool
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%_ptr_Input_bool = OpTypePointer Input %bool
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%sk_Clockwise = OpVariable %_ptr_Input_bool Input
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%void = OpTypeVoid
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%11 = OpTypeFunction %void
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%_ptr_Function_float = OpTypePointer Function %float
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%float_1 = OpConstant %float 1
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%float_2 = OpConstant %float 2
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%v2float = OpTypeVector %float 2
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%_ptr_Function_v2float = OpTypePointer Function %v2float
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%29 = OpConstantComposite %v2float %float_1 %float_2
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%31 = OpConstantComposite %v2float %float_1 %float_2
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%float_3 = OpConstant %float 3
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%float_4 = OpConstant %float 4
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%35 = OpConstantComposite %v2float %float_3 %float_4
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%41 = OpConstantComposite %v2float %float_3 %float_4
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%float_1_0 = OpConstant %float 1
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%main = OpFunction %void None %11
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%12 = OpLabel
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%_1_x = OpVariable %_ptr_Function_float Function
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%x = OpVariable %_ptr_Function_float Function
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%_3_x = OpVariable %_ptr_Function_v2float Function
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%y = OpVariable %_ptr_Function_v2float Function
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OpStore %_1_x %float_1
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%16 = OpExtInst %float %1 Length %float_1
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OpStore %_1_x %16
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%18 = OpLoad %float %_1_x
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%17 = OpExtInst %float %1 Distance %18 %float_2
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OpStore %_1_x %17
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%21 = OpLoad %float %_1_x
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%20 = OpFMul %float %21 %float_2
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OpStore %_1_x %20
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%23 = OpLoad %float %_1_x
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%22 = OpExtInst %float %1 Normalize %23
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OpStore %_1_x %22
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%25 = OpLoad %float %_1_x
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OpStore %x %25
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OpStore %_3_x %29
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%30 = OpExtInst %float %1 Length %31
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%32 = OpCompositeConstruct %v2float %30 %30
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OpStore %_3_x %32
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%34 = OpLoad %v2float %_3_x
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%33 = OpExtInst %float %1 Distance %34 %35
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%38 = OpCompositeConstruct %v2float %33 %33
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OpStore %_3_x %38
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%40 = OpLoad %v2float %_3_x
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%39 = OpDot %float %40 %41
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%42 = OpCompositeConstruct %v2float %39 %39
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OpStore %_3_x %42
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%44 = OpLoad %v2float %_3_x
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%43 = OpExtInst %v2float %1 Normalize %44
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OpStore %_3_x %43
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%46 = OpLoad %v2float %_3_x
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OpStore %y %46
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%47 = OpLoad %float %x
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%48 = OpLoad %v2float %y
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%49 = OpCompositeExtract %float %48 0
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%50 = OpCompositeExtract %float %48 1
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%52 = OpCompositeConstruct %v4float %47 %49 %50 %float_1_0
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OpStore %sk_FragColor %52
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OpReturn
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OpFunctionEnd
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