skia2/tests/sksl/shared/Ossfuzz37677.asm.frag
John Stiles bb8cf5804c Fix invalid variable ref-kind discovered by fuzzer.
No-op arithmetic simplification will convert expressions like `x += 0`
to `x`. When making this simplification, we will also downgrade the ref-
kind of `x` from "write" to "read" since the new expression is no longer
an assignment.

The fuzzer discovered that the ref-kind downgrade was too aggressive,
and would also traverse into nested subexpressions and downgrade them
as well. That is, for `x[y=z] += 0` would convert both `x` and `y`
into "read" references, which is incorrect; `y` is still being written
to.

The fuzzer managed to turn this mistake into an assertion by leveraging
a separate optimization. It added a leading, side-effect-less comma
expression for us to detect as worthless and eliminate. In doing so, we
clone the expression with the busted ref-kind, triggering an assertion.

Change-Id: I42fc31f6932f679ae875e2b49db2ad2f4e89e2cb
Bug: oss-fuzz:37677
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/442536
Auto-Submit: John Stiles <johnstiles@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
2021-08-27 14:01:21 +00:00

74 lines
2.5 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 %_UniformBuffer "_UniformBuffer"
OpMemberName %_UniformBuffer 0 "colorGreen"
OpName %_entrypoint_v "_entrypoint_v"
OpName %main "main"
OpName %x "x"
OpName %y "y"
OpName %z "z"
OpDecorate %sk_FragColor RelaxedPrecision
OpDecorate %sk_FragColor Location 0
OpDecorate %sk_FragColor Index 0
OpDecorate %sk_Clockwise BuiltIn FrontFacing
OpMemberDecorate %_UniformBuffer 0 Offset 0
OpMemberDecorate %_UniformBuffer 0 RelaxedPrecision
OpDecorate %_UniformBuffer Block
OpDecorate %10 Binding 0
OpDecorate %10 DescriptorSet 0
OpDecorate %_arr_int_int_1 ArrayStride 16
OpDecorate %40 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
%_UniformBuffer = OpTypeStruct %v4float
%_ptr_Uniform__UniformBuffer = OpTypePointer Uniform %_UniformBuffer
%10 = OpVariable %_ptr_Uniform__UniformBuffer Uniform
%void = OpTypeVoid
%15 = OpTypeFunction %void
%v2float = OpTypeVector %float 2
%float_0 = OpConstant %float 0
%19 = OpConstantComposite %v2float %float_0 %float_0
%_ptr_Function_v2float = OpTypePointer Function %v2float
%23 = OpTypeFunction %v4float %_ptr_Function_v2float
%int = OpTypeInt 32 1
%int_1 = OpConstant %int 1
%_arr_int_int_1 = OpTypeArray %int %int_1
%_ptr_Function__arr_int_int_1 = OpTypePointer Function %_arr_int_int_1
%_ptr_Function_int = OpTypePointer Function %int
%int_0 = OpConstant %int 0
%_ptr_Uniform_v4float = OpTypePointer Uniform %v4float
%_entrypoint_v = OpFunction %void None %15
%16 = OpLabel
%20 = OpVariable %_ptr_Function_v2float Function
OpStore %20 %19
%22 = OpFunctionCall %v4float %main %20
OpStore %sk_FragColor %22
OpReturn
OpFunctionEnd
%main = OpFunction %v4float None %23
%24 = OpFunctionParameter %_ptr_Function_v2float
%25 = OpLabel
%x = OpVariable %_ptr_Function__arr_int_int_1 Function
%y = OpVariable %_ptr_Function_int Function
%z = OpVariable %_ptr_Function_int Function
OpStore %y %int_0
OpStore %z %int_0
%35 = OpLoad %int %z
OpStore %y %35
%36 = OpAccessChain %_ptr_Function_int %x %35
%37 = OpLoad %int %36
%38 = OpAccessChain %_ptr_Uniform_v4float %10 %int_0
%40 = OpLoad %v4float %38
OpReturnValue %40
OpFunctionEnd