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Generate correctly structured do-while loops.

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The loop test is always emitted before the loop body.

For do-while loops, use a phi node to track whether we're
on the first loop iteration, and only check the loop test
on the second and subsequent iterations.

For do-while loops, the loop test branch no longer occurs
at the top of the loop, so it must get its own selection
merge instruction.

A block can't be the target of more than one merge instruction.
So when the loop test executes after the body (as in do-while in GLSL)
we need to introduce a dummy block to be the target of the selection
merge just before the loop test conditional branch.

The other arm of the branch exits the loop and hence is the
"break block" exception in the structured control flow rules.
This commit is contained in:
David Neto
2015-07-15 16:21:26 -04:00
parent 51b31b5785
commit c22f37cfb4
8 changed files with 1486 additions and 1373 deletions
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65
Test/baseResults/spv.doWhileLoop.frag.out
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@@ -5,7 +5,7 @@ Linked fragment stage:
// Module Version 99
// Generated by (magic number): 51a00bb
// Id's are bound by 34
// Id's are bound by 38
Source GLSL 110
1: ExtInstImport "GLSL.std.450"
@@ -14,11 +14,11 @@ Linked fragment stage:
Name 4 "main"
Name 10 "color"
Name 12 "BaseColor"
Name 19 "bigColor"
Name 26 "d"
Name 32 "gl_FragColor"
Name 25 "d"
Name 30 "bigColor"
Name 36 "gl_FragColor"
Decorate 12(BaseColor) Smooth
Decorate 32(gl_FragColor) BuiltIn FragColor
Decorate 36(gl_FragColor) BuiltIn FragColor
2: TypeVoid
3: TypeFunction 2
7: TypeFloat 32
@@ -26,13 +26,15 @@ Linked fragment stage:
9: TypePointer Function 8(fvec4)
11: TypePointer Input 8(fvec4)
12(BaseColor): 11(ptr) Variable Input
18: TypePointer UniformConstant 8(fvec4)
19(bigColor): 18(ptr) Variable UniformConstant
25: TypePointer UniformConstant 7(float)
26(d): 25(ptr) Variable UniformConstant
28: TypeBool
31: TypePointer Output 8(fvec4)
32(gl_FragColor): 31(ptr) Variable Output
17: TypeBool
18: 17(bool) ConstantTrue
24: TypePointer UniformConstant 7(float)
25(d): 24(ptr) Variable UniformConstant
29: TypePointer UniformConstant 8(fvec4)
30(bigColor): 29(ptr) Variable UniformConstant
34: 17(bool) ConstantFalse
35: TypePointer Output 8(fvec4)
36(gl_FragColor): 35(ptr) Variable Output
4(main): 2 Function None 3
5: Label
10(color): 9(ptr) Variable Function
@@ -40,25 +42,30 @@ Linked fragment stage:
Store 10(color) 13
Branch 14
14: Label
16: 17(bool) Phi 18 5 34 20
LoopMerge 15 None
Branch 16
16: Label
20: 8(fvec4) Load 19(bigColor)
21: 8(fvec4) Load 10(color)
22: 8(fvec4) FAdd 21 20
Store 10(color) 22
Branch 17
17: Label
23: 8(fvec4) Load 10(color)
24: 7(float) CompositeExtract 23 0
27: 7(float) Load 26(d)
29: 28(bool) FOrdLessThan 24 27
BranchConditional 29 30 15
30: Label
Branch 14
Branch 19
19: Label
SelectionMerge 20 None
BranchConditional 16 20 21
21: Label
22: 8(fvec4) Load 10(color)
23: 7(float) CompositeExtract 22 0
26: 7(float) Load 25(d)
27: 17(bool) FOrdLessThan 23 26
SelectionMerge 28 None
BranchConditional 27 28 15
28: Label
Branch 20
20: Label
31: 8(fvec4) Load 30(bigColor)
32: 8(fvec4) Load 10(color)
33: 8(fvec4) FAdd 32 31
Store 10(color) 33
Branch 14
15: Label
33: 8(fvec4) Load 10(color)
Store 32(gl_FragColor) 33
37: 8(fvec4) Load 10(color)
Store 36(gl_FragColor) 37
Branch 6
6: Label
Return