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Split loop header from condition testing for for/while loops.

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This commit is contained in:
Dejan Mircevski
2016-01-20 11:51:43 -05:00
parent 7349eab099
commit 213bbbe4a7
14 changed files with 1905 additions and 1828 deletions
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22
SPIRV/GlslangToSpv.cpp
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@@ -1391,12 +1391,22 @@ bool TGlslangToSpvTraverser::visitLoop(glslang::TVisit /* visit */, glslang::TIn
{
auto blocks = builder.makeNewLoop();
builder.createBranch(&blocks.head);
// Spec requires back edges to target header blocks, and every header block
// must dominate its merge block. Make a header block first to ensure these
// conditions are met. By definition, it will contain OpLoopMerge, followed
// by a block-ending branch. But we don't want to put any other body/test
// instructions in it, since the body/test may have arbitrary instructions,
// including merges of its own.
builder.setBuildPoint(&blocks.head);
builder.createLoopMerge(&blocks.merge, &blocks.continue_target, spv::LoopControlMaskNone);
if (node->testFirst() && node->getTest()) {
builder.setBuildPoint(&blocks.head);
spv::Block& test = builder.makeNewBlock();
builder.createBranch(&test);
builder.setBuildPoint(&test);
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.setBuildPoint(&blocks.body);
@@ -1411,14 +1421,6 @@ bool TGlslangToSpvTraverser::visitLoop(glslang::TVisit /* visit */, glslang::TIn
node->getTerminal()->traverse(this);
builder.createBranch(&blocks.head);
} else {
// Spec requires back edges to target header blocks, and every header
// block must dominate its merge block. Make a header block first to
// ensure these conditions are met. By definition, it will contain
// OpLoopMerge, followed by a block-ending branch. But we don't want to
// put any other body instructions in it, since the body may have
// arbitrary instructions, including merges of its own.
builder.setBuildPoint(&blocks.head);
builder.createLoopMerge(&blocks.merge, &blocks.continue_target, spv::LoopControlMaskNone);
builder.createBranch(&blocks.body);
breakForLoop.push(true);