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SPIR-V: Return undefined values from implicit returns instead of dummy

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Previously if a non-void function implictly returned, a dummy variable
was created as return value. Now instead it returns the result of the
OpUndef instruction. This better conveys the presence of undefined
behavior to SPIR-V consuming tools (and humans).

It also saves one ID per occurrence...
This commit is contained in:
Miro Knejp 2015-08-11 02:45:24 +02:00
parent 65c78a0b62
commit 28f9b1c28d
4 changed files with 77 additions and 74 deletions
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12
SPIRV/SpvBuilder.cpp
View File

@ -791,9 +791,7 @@ void Builder::leaveFunction(bool main)
if (function.getReturnType() == makeVoidType()) if (function.getReturnType() == makeVoidType())
makeReturn(true); makeReturn(true);
else { else {
Id retStorage = createVariable(StorageClassFunction, function.getReturnType(), "dummyReturn"); makeReturn(true, createUndefined(function.getReturnType()));
Id retValue = createLoad(retStorage);
makeReturn(true, retValue);
} }
} }
} }
@ -844,6 +842,14 @@ Id Builder::createVariable(StorageClass storageClass, Id type, const char* name)
return inst->getResultId(); return inst->getResultId();
} }
// Comments in header
Id Builder::createUndefined(Id type)
{
Instruction* inst = new Instruction(getUniqueId(), type, OpUndef);
buildPoint->addInstruction(inst);
return inst->getResultId();
}
// Comments in header // Comments in header
void Builder::createStore(Id rValue, Id lValue) void Builder::createStore(Id rValue, Id lValue)
{ {

3
SPIRV/SpvBuilder.h
View File

@ -218,6 +218,9 @@ public:
// Create a global or function local or IO variable. // Create a global or function local or IO variable.
Id createVariable(StorageClass, Id type, const char* name = 0); Id createVariable(StorageClass, Id type, const char* name = 0);
// Create an imtermediate with an undefined value.
Id createUndefined(Id type);
// Store into an Id and return the l-value // Store into an Id and return the l-value
void createStore(Id rValue, Id lValue); void createStore(Id rValue, Id lValue);

30
Test/baseResults/spv.forwardFun.frag.out Executable file → Normal file
View File

@ -5,7 +5,7 @@ Linked fragment stage:
// Module Version 99 // Module Version 99
// Generated by (magic number): 51a00bb // Generated by (magic number): 51a00bb
// Id's are bound by 59 // Id's are bound by 58
Source ESSL 100 Source ESSL 100
Capability Shader Capability Shader
@ -24,8 +24,7 @@ Linked fragment stage:
Name 28 "f" Name 28 "f"
Name 31 "gl_FragColor" Name 31 "gl_FragColor"
Name 37 "d" Name 37 "d"
Name 49 "dummyReturn" Name 57 "bigColor"
Name 58 "bigColor"
Decorate 19(color) RelaxedPrecision Decorate 19(color) RelaxedPrecision
Decorate 21(BaseColor) RelaxedPrecision Decorate 21(BaseColor) RelaxedPrecision
Decorate 21(BaseColor) Smooth Decorate 21(BaseColor) Smooth
@ -33,8 +32,8 @@ Linked fragment stage:
Decorate 31(gl_FragColor) RelaxedPrecision Decorate 31(gl_FragColor) RelaxedPrecision
Decorate 31(gl_FragColor) BuiltIn FragColor Decorate 31(gl_FragColor) BuiltIn FragColor
Decorate 37(d) RelaxedPrecision Decorate 37(d) RelaxedPrecision
Decorate 58(bigColor) RelaxedPrecision Decorate 57(bigColor) RelaxedPrecision
Decorate 58(bigColor) NoStaticUse Decorate 57(bigColor) NoStaticUse
2: TypeVoid 2: TypeVoid
3: TypeFunction 2 3: TypeFunction 2
9: TypeFloat 32 9: TypeFloat 32
@ -53,8 +52,8 @@ Linked fragment stage:
40: TypeBool 40: TypeBool
44: 9(float) Constant 1067030938 44: 9(float) Constant 1067030938
47: 9(float) Constant 1083179008 47: 9(float) Constant 1083179008
57: TypePointer UniformConstant 13(fvec4) 56: TypePointer UniformConstant 13(fvec4)
58(bigColor): 57(ptr) Variable UniformConstant 57(bigColor): 56(ptr) Variable UniformConstant
4(main): 2 Function None 3 4(main): 2 Function None 3
5: Label 5: Label
19(color): 14(ptr) Variable Function 19(color): 14(ptr) Variable Function
@ -82,7 +81,6 @@ Linked fragment stage:
FunctionEnd FunctionEnd
11(unreachableReturn(): 9(float) Function None 10 11(unreachableReturn(): 9(float) Function None 10
12: Label 12: Label
49(dummyReturn): 27(ptr) Variable Function
35: 2 FunctionCall 7(bar() 35: 2 FunctionCall 7(bar()
38: 9(float) Load 37(d) 38: 9(float) Load 37(d)
41: 40(bool) FOrdLessThan 38 39 41: 40(bool) FOrdLessThan 38 39
@ -93,16 +91,16 @@ Linked fragment stage:
46: Label 46: Label
ReturnValue 47 ReturnValue 47
43: Label 43: Label
50: 9(float) Load 49(dummyReturn) 49: 9(float) Undef
ReturnValue 50 ReturnValue 49
FunctionEnd FunctionEnd
17(foo(vf4;): 9(float) Function None 15 17(foo(vf4;): 9(float) Function None 15
16(bar): 14(ptr) FunctionParameter 16(bar): 14(ptr) FunctionParameter
18: Label 18: Label
51: 13(fvec4) Load 16(bar) 50: 13(fvec4) Load 16(bar)
52: 9(float) CompositeExtract 51 0 51: 9(float) CompositeExtract 50 0
53: 13(fvec4) Load 16(bar) 52: 13(fvec4) Load 16(bar)
54: 9(float) CompositeExtract 53 1 53: 9(float) CompositeExtract 52 1
55: 9(float) FAdd 52 54 54: 9(float) FAdd 51 53
ReturnValue 55 ReturnValue 54
FunctionEnd FunctionEnd

104
Test/baseResults/spv.functionCall.frag.out Executable file → Normal file
View File

@ -7,7 +7,7 @@ Linked fragment stage:
// Module Version 99 // Module Version 99
// Generated by (magic number): 51a00bb // Generated by (magic number): 51a00bb
// Id's are bound by 76 // Id's are bound by 74
Source GLSL 130 Source GLSL 130
Capability Shader Capability Shader
@ -23,18 +23,16 @@ Linked fragment stage:
Name 19 "missingReturn(" Name 19 "missingReturn("
Name 22 "h" Name 22 "h"
Name 31 "d" Name 31 "d"
Name 44 "dummyReturn" Name 52 "color"
Name 53 "dummyReturn" Name 54 "BaseColor"
Name 55 "color" Name 55 "param"
Name 57 "BaseColor" Name 61 "f"
Name 58 "param" Name 63 "g"
Name 63 "f" Name 66 "gl_FragColor"
Name 65 "g" Name 73 "bigColor"
Name 68 "gl_FragColor" Decorate 54(BaseColor) Smooth
Name 75 "bigColor" Decorate 66(gl_FragColor) BuiltIn FragColor
Decorate 57(BaseColor) Smooth Decorate 73(bigColor) NoStaticUse
Decorate 68(gl_FragColor) BuiltIn FragColor
Decorate 75(bigColor) NoStaticUse
2: TypeVoid 2: TypeVoid
3: TypeFunction 2 3: TypeFunction 2
7: TypeFloat 32 7: TypeFloat 32
@ -51,37 +49,37 @@ Linked fragment stage:
34: TypeBool 34: TypeBool
38: 7(float) Constant 1067030938 38: 7(float) Constant 1067030938
41: 7(float) Constant 1083179008 41: 7(float) Constant 1083179008
43: TypePointer Function 7(float) 49: 7(float) Constant 1081711002
51: 7(float) Constant 1081711002 53: TypePointer Input 8(fvec4)
56: TypePointer Input 8(fvec4) 54(BaseColor): 53(ptr) Variable Input
57(BaseColor): 56(ptr) Variable Input 60: TypePointer Function 7(float)
67: TypePointer Output 8(fvec4) 65: TypePointer Output 8(fvec4)
68(gl_FragColor): 67(ptr) Variable Output 66(gl_FragColor): 65(ptr) Variable Output
74: TypePointer UniformConstant 8(fvec4) 72: TypePointer UniformConstant 8(fvec4)
75(bigColor): 74(ptr) Variable UniformConstant 73(bigColor): 72(ptr) Variable UniformConstant
4(main): 2 Function None 3 4(main): 2 Function None 3
5: Label 5: Label
55(color): 9(ptr) Variable Function 52(color): 9(ptr) Variable Function
58(param): 9(ptr) Variable Function 55(param): 9(ptr) Variable Function
63(f): 43(ptr) Variable Function 61(f): 60(ptr) Variable Function
65(g): 43(ptr) Variable Function 63(g): 60(ptr) Variable Function
Store 22(h) 23 Store 22(h) 23
59: 8(fvec4) Load 57(BaseColor) 56: 8(fvec4) Load 54(BaseColor)
Store 58(param) 59 Store 55(param) 56
60: 7(float) FunctionCall 12(foo(vf4;) 58(param) 57: 7(float) FunctionCall 12(foo(vf4;) 55(param)
61: 8(fvec4) CompositeConstruct 60 60 60 60 58: 8(fvec4) CompositeConstruct 57 57 57 57
Store 55(color) 61 Store 52(color) 58
62: 2 FunctionCall 14(bar() 59: 2 FunctionCall 14(bar()
64: 7(float) FunctionCall 17(unreachableReturn() 62: 7(float) FunctionCall 17(unreachableReturn()
Store 63(f) 64 Store 61(f) 62
66: 7(float) FunctionCall 19(missingReturn() 64: 7(float) FunctionCall 19(missingReturn()
Store 65(g) 66 Store 63(g) 64
69: 8(fvec4) Load 55(color) 67: 8(fvec4) Load 52(color)
70: 7(float) Load 63(f) 68: 7(float) Load 61(f)
69: 8(fvec4) VectorTimesScalar 67 68
70: 7(float) Load 22(h)
71: 8(fvec4) VectorTimesScalar 69 70 71: 8(fvec4) VectorTimesScalar 69 70
72: 7(float) Load 22(h) Store 66(gl_FragColor) 71
73: 8(fvec4) VectorTimesScalar 71 72
Store 68(gl_FragColor) 73
Branch 6 Branch 6
6: Label 6: Label
Return Return
@ -102,7 +100,6 @@ Linked fragment stage:
FunctionEnd FunctionEnd
17(unreachableReturn(): 7(float) Function None 16 17(unreachableReturn(): 7(float) Function None 16
18: Label 18: Label
44(dummyReturn): 43(ptr) Variable Function
32: 7(float) Load 31(d) 32: 7(float) Load 31(d)
35: 34(bool) FOrdLessThan 32 33 35: 34(bool) FOrdLessThan 32 33
SelectionMerge 37 None SelectionMerge 37 None
@ -112,21 +109,20 @@ Linked fragment stage:
40: Label 40: Label
ReturnValue 41 ReturnValue 41
37: Label 37: Label
45: 7(float) Load 44(dummyReturn) 43: 7(float) Undef
ReturnValue 45 ReturnValue 43
FunctionEnd FunctionEnd
19(missingReturn(): 7(float) Function None 16 19(missingReturn(): 7(float) Function None 16
20: Label 20: Label
53(dummyReturn): 43(ptr) Variable Function 44: 7(float) Load 31(d)
46: 7(float) Load 31(d) 45: 34(bool) FOrdLessThan 44 41
47: 34(bool) FOrdLessThan 46 41 SelectionMerge 47 None
SelectionMerge 49 None BranchConditional 45 46 47
BranchConditional 47 48 49 46: Label
48: Label 48: 7(float) Load 31(d)
50: 7(float) Load 31(d) Store 22(h) 48
Store 22(h) 50 ReturnValue 49
47: Label
51: 7(float) Undef
ReturnValue 51 ReturnValue 51
49: Label
54: 7(float) Load 53(dummyReturn)
ReturnValue 54
FunctionEnd FunctionEnd