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Fix switch fallthrough case in some cases.

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This commit is contained in:
Hans-Kristian Arntzen 2021-08-31 17:24:09 +02:00
parent 0e2880ab99
commit 23c4480d8e
3 changed files with 214 additions and 17 deletions
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88
reference/shaders-no-opt/asm/frag/switch-non-default-fallthrough-no-phi.asm.frag Normal file
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@ -0,0 +1,88 @@
#version 450
struct _4
{
uint _m0;
int _m1;
};
struct _5
{
int _m0;
int _m1;
};
layout(location = 0) flat in int _2;
layout(location = 0) out int _3;
_4 _16;
int _21;
void main()
{
bool _25 = false;
do
{
_5 _26;
_26._m0 = 0;
_26._m1 = 10;
_4 _35;
_35 = _16;
int _39;
_4 _36;
bool _59;
int _38 = 0;
for (;;)
{
if (_26._m0 < _26._m1)
{
int _27 = _26._m0;
int _28 = _26._m0 + int(1u);
_26._m0 = _28;
_36 = _4(1u, _27);
}
else
{
_4 _48 = _35;
_48._m0 = 0u;
_36 = _48;
}
bool _45_ladder_break = false;
switch (int(_36._m0))
{
case 0:
{
_3 = _38;
_25 = true;
_59 = true;
_45_ladder_break = true;
break;
}
default:
{
_59 = false;
_45_ladder_break = true;
break;
}
case 1:
{
break;
}
}
if (_45_ladder_break)
{
break;
}
_39 = _38 + _2;
_35 = _36;
_38 = _39;
continue;
}
if (_59)
{
break;
}
break;
} while(false);
}

105
shaders-no-opt/asm/frag/switch-non-default-fallthrough-no-phi.asm.frag Normal file
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@ -0,0 +1,105 @@
; SPIR-V
; Version: 1.3
; Generator: Google rspirv; 0
; Bound: 80
; Schema: 0
OpCapability Shader
OpCapability VulkanMemoryModel
OpExtension "SPV_KHR_vulkan_memory_model"
OpMemoryModel Logical Vulkan
OpEntryPoint Fragment %1 "main" %2 %3
OpExecutionMode %1 OriginUpperLeft
OpMemberDecorate %_struct_14 0 Offset 0
OpMemberDecorate %_struct_14 1 Offset 4
OpMemberDecorate %_struct_15 0 Offset 0
OpMemberDecorate %_struct_15 1 Offset 4
OpDecorate %2 Location 0
OpDecorate %3 Location 0
OpDecorate %2 Flat
%int = OpTypeInt 32 1
%uint = OpTypeInt 32 0
%bool = OpTypeBool
%_ptr_Input_int = OpTypePointer Input %int
%_ptr_Output_int = OpTypePointer Output %int
%_ptr_Function_int = OpTypePointer Function %int
%void = OpTypeVoid
%_struct_14 = OpTypeStruct %uint %int
%_struct_15 = OpTypeStruct %int %int
%_ptr_Function__struct_15 = OpTypePointer Function %_struct_15
%24 = OpTypeFunction %void
%2 = OpVariable %_ptr_Input_int Input
%3 = OpVariable %_ptr_Output_int Output
%uint_1 = OpConstant %uint 1
%26 = OpUndef %_struct_14
%uint_0 = OpConstant %uint 0
%int_0 = OpConstant %int 0
%int_10 = OpConstant %int 10
%true = OpConstantTrue %bool
%31 = OpUndef %int
%false = OpConstantFalse %bool
%_ptr_Function_bool = OpTypePointer Function %bool
%1 = OpFunction %void None %24
%32 = OpLabel
%76 = OpVariable %_ptr_Function_bool Function %false
%33 = OpVariable %_ptr_Function__struct_15 Function
%34 = OpVariable %_ptr_Function_int Function
%35 = OpVariable %_ptr_Function_int Function
OpSelectionMerge %72 None
OpSwitch %uint_0 %73
%73 = OpLabel
%36 = OpLoad %int %2
%37 = OpAccessChain %_ptr_Function_int %33 %uint_0
OpStore %37 %int_0
%38 = OpAccessChain %_ptr_Function_int %33 %uint_1
OpStore %38 %int_10
OpBranch %40
%40 = OpLabel
%41 = OpPhi %_struct_14 %26 %73 %42 %43
%44 = OpPhi %int %int_0 %73 %45 %43
OpLoopMerge %48 %43 None
OpBranch %49
%49 = OpLabel
%52 = OpLoad %int %37
%53 = OpLoad %int %38
%54 = OpSLessThan %bool %52 %53
OpSelectionMerge %55 None
OpBranchConditional %54 %56 %57
%57 = OpLabel
%65 = OpCompositeInsert %_struct_14 %uint_0 %41 0
OpBranch %55
%56 = OpLabel
%59 = OpLoad %int %37
%60 = OpBitcast %int %uint_1
%61 = OpIAdd %int %59 %60
OpCopyMemory %34 %37
%63 = OpLoad %int %34
OpStore %35 %61
OpCopyMemory %37 %35
%64 = OpCompositeConstruct %_struct_14 %uint_1 %63
OpBranch %55
%55 = OpLabel
%42 = OpPhi %_struct_14 %64 %56 %65 %57
%66 = OpCompositeExtract %uint %42 0
%67 = OpBitcast %int %66
OpSelectionMerge %71 None
OpSwitch %67 %69 0 %70 1 %71
%71 = OpLabel
%45 = OpIAdd %int %44 %36
OpBranch %43
%70 = OpLabel
OpStore %3 %44
OpStore %76 %true
OpBranch %48
%69 = OpLabel
OpBranch %48
%43 = OpLabel
OpBranch %40
%48 = OpLabel
%79 = OpPhi %bool %false %69 %true %70
OpSelectionMerge %77 None
OpBranchConditional %79 %72 %77
%77 = OpLabel
OpBranch %72
%72 = OpLabel
OpReturn
OpFunctionEnd

38
spirv_glsl.cpp
View File

@ -14974,26 +14974,30 @@ void CompilerGLSL::emit_block_chain(SPIRBlock &block)
}
// Might still have to flush phi variables if we branch from loop header directly to merge target.
if (flush_phi_required(block.self, block.next_block))
// This is supposed to emit all cases where we branch from header to merge block directly.
// There are two main scenarios where cannot rely on default fallthrough.
// - There is an explicit default: label already.
// In this case, literals_to_merge need to form their own "default" case, so that we avoid executing that block.
// - Header -> Merge requires flushing PHI. In this case, we need to collect all cases and flush PHI there.
bool header_merge_requires_phi = flush_phi_required(block.self, block.next_block);
bool need_fallthrough_block = block.default_block == block.next_block || !literals_to_merge.empty();
if ((header_merge_requires_phi && need_fallthrough_block) || !literals_to_merge.empty())
{
if (block.default_block == block.next_block || !literals_to_merge.empty())
for (auto &case_literal : literals_to_merge)
statement("case ", to_case_label(case_literal, unsigned_case), label_suffix, ":");
if (block.default_block == block.next_block)
{
for (auto &case_literal : literals_to_merge)
statement("case ", to_case_label(case_literal, unsigned_case), label_suffix, ":");
if (block.default_block == block.next_block)
{
if (is_legacy_es())
statement("else");
else
statement("default:");
}
begin_scope();
flush_phi(block.self, block.next_block);
statement("break;");
end_scope();
if (is_legacy_es())
statement("else");
else
statement("default:");
}
begin_scope();
flush_phi(block.self, block.next_block);
statement("break;");
end_scope();
}
if (degenerate_switch && !is_legacy_es())