BeeEngine/glslang-zig
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

Fix back-branch target for do-while loops.

Browse source 
To ensure back branches always go to a header block, create a header
block even for !testFirst loops.  Then unify common code between the
testFirst/!testFirst cases.

Generate the header-block code first, so update golden files.

Realize that certain infinite loops generate invalid SPIR-V, so put a
TODO to instead abort code generation in such cases.

Change-Id: I1e173c8f73daad186cfc666b7d72bd563ed7665d
This commit is contained in:
Dejan Mircevski 2016-01-11 15:57:11 -05:00
parent c8fbbab419
commit 832c65c33b
20 changed files with 2062 additions and 2029 deletions
Download patch file Download diff file Expand all files Collapse all files

29
SPIRV/GlslangToSpv.cpp
View file

@ -1342,19 +1342,17 @@ void TGlslangToSpvTraverser::visitConstantUnion(glslang::TIntermConstantUnion* n
bool TGlslangToSpvTraverser::visitLoop(glslang::TVisit /* visit */, glslang::TIntermLoop* node)
{
auto blocks = builder.makeNewLoop();
builder.createBranch(&blocks.head);
if (node->testFirst() && node->getTest()) {
spv::Block& head = builder.makeNewBlock();
builder.createBranch(&head);
builder.setBuildPoint(&head);
builder.setBuildPoint(&blocks.head);
node->getTest()->traverse(this);
spv::Id condition =
builder.accessChainLoad(convertGlslangToSpvType(node->getTest()->getType()));
builder.createLoopMerge(&blocks.merge, &blocks.continue_target, spv::LoopControlMaskNone);
builder.createConditionalBranch(condition, &blocks.body, &blocks.merge);
breakForLoop.push(true);
builder.setBuildPoint(&blocks.body);
breakForLoop.push(true);
if (node->getBody())
node->getBody()->traverse(this);
builder.createBranch(&blocks.continue_target);
@ -1363,8 +1361,14 @@ bool TGlslangToSpvTraverser::visitLoop(glslang::TVisit /* visit */, glslang::TIn
builder.setBuildPoint(&blocks.continue_target);
if (node->getTerminal())
node->getTerminal()->traverse(this);
builder.createBranch(&head);
builder.createBranch(&blocks.head);
} else {
// Spec requires back edges to target header blocks, and every header
// block must dominate its merge block. Create an empty header block
// here to ensure these conditions are met even when body contains
// non-trivial control flow.
builder.setBuildPoint(&blocks.head);
builder.createLoopMerge(&blocks.merge, &blocks.continue_target, spv::LoopControlMaskNone);
builder.createBranch(&blocks.body);
breakForLoop.push(true);
@ -1381,14 +1385,17 @@ bool TGlslangToSpvTraverser::visitLoop(glslang::TVisit /* visit */, glslang::TIn
node->getTest()->traverse(this);
spv::Id condition =
builder.accessChainLoad(convertGlslangToSpvType(node->getTest()->getType()));
builder.createLoopMerge(&blocks.merge, &blocks.continue_target,
spv::LoopControlMaskNone);
builder.createConditionalBranch(condition, &blocks.body, &blocks.merge);
builder.createConditionalBranch(condition, &blocks.head, &blocks.merge);
} else {
builder.createBranch(&blocks.body);
// TODO: unless there was a break instruction somewhere in the body,
// this is an infinite loop, so we should abort code generation with
// a warning. As it stands now, nothing will jump to the merge
// block, and it may be dropped as unreachable by the SPIR-V dumper.
// That, in turn, will result in a non-existing %ID in the LoopMerge
// above.
builder.createBranch(&blocks.head);
}
}
builder.setBuildPoint(&blocks.merge);
builder.closeLoop();
return false;