Fix TextureUpgradeAndSamplerRemovalTransform when used with qualifiers

The transform removes sampler arguments from functions and function calls; this causes function arguments to change their indices. When some function arguments have an output qualifier, this qualifier can get lost because of the removal which can lead to incorrect results (e.g. out qualifier not having effect). To fix this we iterate through both seq & qual arrays in lock-step and manually remove/replace entries as appropriate.

Fix TextureUpgradeAndSamplerRemovalTransform when used with qualifiers
b239d22f · Arseny Kapoulkine · 2fb966aa · b239d22f
Commit b239d22f authored May 21, 2018 by Arseny Kapoulkine
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Showing with 29 additions and 13 deletions

Intermediate.cpp glslang/MachineIndependent/Intermediate.cpp +29 -13

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--- a/glslang/MachineIndependent/Intermediate.cpp
+++ b/glslang/MachineIndependent/Intermediate.cpp
@@ -3769,23 +3769,39 @@ struct TextureUpgradeAndSamplerRemovalTransform : public TIntermTraverser {
    bool visitAggregate(TVisit, TIntermAggregate* ag) override {
        using namespace std;
        TIntermSequence& seq = ag->getSequence();
-        // remove pure sampler variables
+        TQualifierList& qual = ag->getQualifierList();
-        TIntermSequence::iterator newEnd = remove_if(seq.begin(), seq.end(), [](TIntermNode* node) {
-            TIntermSymbol* symbol = node->getAsSymbolNode();
+        // qual and seq are indexed using the same indices, so we have to modify both in lock-step
-            if (!symbol)
+        assert(seq.size() == qual.size() || qual.empty());
-                return false;
+        size_t write = 0;
+        for (size_t i = 0; i < seq.size(); ++i) {
+            TIntermSymbol* symbol = seq[i]->getAsSymbolNode();
+            if (symbol && symbol->getBasicType() == EbtSampler && symbol->getType().getSampler().isPureSampler()) {
+                // remove pure sampler variables
+                continue;
+            }
+            TIntermNode* result = seq[i];
-            return (symbol->getBasicType() == EbtSampler && symbol->getType().getSampler().isPureSampler());
+            // replace constructors with sampler/textures
-        });
+            TIntermAggregate *constructor = seq[i]->getAsAggregate();
-        seq.erase(newEnd, seq.end());
-        // replace constructors with sampler/textures
-        for_each(seq.begin(), seq.end(), [](TIntermNode*& node) {
-            TIntermAggregate *constructor = node->getAsAggregate();
            if (constructor && constructor->getOp() == EOpConstructTextureSampler) {
                if (!constructor->getSequence().empty())
-                    node = constructor->getSequence()[0];
+                    result = constructor->getSequence()[0];
            }
-        });
+            // write new node & qualifier
+            seq[write] = result;
+            if (!qual.empty())
+                qual[write] = qual[i];
+            write++;
+        }
+        seq.resize(write);
+        if (!qual.empty())
+            qual.resize(write);
        return true;
    }
 };