skia2/tests/sksl/shared/UnusedVariables.asm.frag
John Stiles ffc9dec755 Eliminate redundant loads following stores.
We now have two functions `writeOpLoad` and `writeOpStore` which are
in charge of writing SpvOpLoad and SpvOpStore instructions.
`writeOpStore` also keeps track of pointer stores in a "store cache."
Subsequent loads from that same pointer will be found in the cache and
will return the value stored in that pointer instead.

Such a cache definitely cannot work in the face of control flow, so we
make the following concessions:
- `pruneReachableOps` is now `pruneConditionalOps`. Any pointers that
  are altered inside a potentially-unreachable block are cleared from
  the cache entirely.
- The entire store cache is cleared at all OpLabels within a loop.

The cache also cannot work in the presence of swizzled stores, so we
make another significant concession:
- The entire store cache is cleared whenever we store into a non-memory
  pointer (e.g., assigning into a swizzled LValue, such as `foo.xz`).

Despite these significant limitations, this manages to dramatically
shrink many real-world examples.

Change-Id: I0981a0cf7b45b064e153e9ada271494c8e00cad5
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/530054
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: John Stiles <johnstiles@google.com>
Auto-Submit: John Stiles <johnstiles@google.com>
2022-04-18 14:57:48 +00:00

99 lines
2.9 KiB
JavaScript

OpCapability Shader
%1 = OpExtInstImport "GLSL.std.450"
OpMemoryModel Logical GLSL450
OpEntryPoint Fragment %_entrypoint_v "_entrypoint" %sk_FragColor %sk_Clockwise
OpExecutionMode %_entrypoint_v OriginUpperLeft
OpName %sk_FragColor "sk_FragColor"
OpName %sk_Clockwise "sk_Clockwise"
OpName %_entrypoint_v "_entrypoint_v"
OpName %main "main"
OpName %b "b"
OpName %c "c"
OpName %x "x"
OpName %d "d"
OpDecorate %sk_FragColor RelaxedPrecision
OpDecorate %sk_FragColor Location 0
OpDecorate %sk_FragColor Index 0
OpDecorate %sk_Clockwise BuiltIn FrontFacing
OpDecorate %49 RelaxedPrecision
OpDecorate %51 RelaxedPrecision
OpDecorate %54 RelaxedPrecision
OpDecorate %57 RelaxedPrecision
OpDecorate %58 RelaxedPrecision
%float = OpTypeFloat 32
%v4float = OpTypeVector %float 4
%_ptr_Output_v4float = OpTypePointer Output %v4float
%sk_FragColor = OpVariable %_ptr_Output_v4float Output
%bool = OpTypeBool
%_ptr_Input_bool = OpTypePointer Input %bool
%sk_Clockwise = OpVariable %_ptr_Input_bool Input
%void = OpTypeVoid
%12 = OpTypeFunction %void
%float_0 = OpConstant %float 0
%v2float = OpTypeVector %float 2
%16 = OpConstantComposite %v2float %float_0 %float_0
%_ptr_Function_v2float = OpTypePointer Function %v2float
%20 = OpTypeFunction %v4float %_ptr_Function_v2float
%_ptr_Function_float = OpTypePointer Function %float
%float_2 = OpConstant %float 2
%float_3 = OpConstant %float 3
%int = OpTypeInt 32 1
%_ptr_Function_int = OpTypePointer Function %int
%int_0 = OpConstant %int 0
%int_1 = OpConstant %int 1
%float_1 = OpConstant %float 1
%float_5 = OpConstant %float 5
%float_4 = OpConstant %float 4
%_entrypoint_v = OpFunction %void None %12
%13 = OpLabel
%17 = OpVariable %_ptr_Function_v2float Function
OpStore %17 %16
%19 = OpFunctionCall %v4float %main %17
OpStore %sk_FragColor %19
OpReturn
OpFunctionEnd
%main = OpFunction %v4float None %20
%21 = OpFunctionParameter %_ptr_Function_v2float
%22 = OpLabel
%b = OpVariable %_ptr_Function_float Function
%c = OpVariable %_ptr_Function_float Function
%x = OpVariable %_ptr_Function_int Function
%d = OpVariable %_ptr_Function_float Function
OpStore %b %float_2
OpStore %c %float_3
OpStore %x %int_0
OpBranch %32
%32 = OpLabel
OpLoopMerge %36 %35 None
OpBranch %33
%33 = OpLabel
%37 = OpLoad %int %x
%39 = OpSLessThan %bool %37 %int_1
OpBranchConditional %39 %34 %36
%34 = OpLabel
OpBranch %35
%35 = OpLabel
%40 = OpLoad %int %x
%41 = OpIAdd %int %40 %int_1
OpStore %x %41
OpBranch %32
%36 = OpLabel
%43 = OpLoad %float %c
OpStore %d %43
%44 = OpLoad %float %b
%46 = OpFAdd %float %44 %float_1
OpStore %b %46
%47 = OpFAdd %float %43 %float_1
OpStore %d %47
%48 = OpFOrdEqual %bool %46 %float_2
%49 = OpSelect %float %48 %float_1 %float_0
%50 = OpFOrdEqual %bool %46 %float_3
%51 = OpSelect %float %50 %float_1 %float_0
%53 = OpFOrdEqual %bool %47 %float_5
%54 = OpSelect %float %53 %float_1 %float_0
%56 = OpFOrdEqual %bool %47 %float_4
%57 = OpSelect %float %56 %float_1 %float_0
%58 = OpCompositeConstruct %v4float %49 %51 %54 %57
OpReturnValue %58
OpFunctionEnd