From 9653dcc2c9d5d20d3d0e8918aaf1d5b09e963060 Mon Sep 17 00:00:00 2001
From: jsmall-nvidia <jsmall@nvidia.com>
Date: Tue, 3 Dec 2019 09:58:59 -0500
Subject: getStringHash on string literals (#1140)

* WIP getStringHash

* Have a use.

* Add slang-string-hash.h/.cpp

* Use StringSlicePool for holding strings for StringHash.
Add outputBuffer to string-literal-hash.slang so value can be tested.
Ignore the GlobalHashedStringLiterals instruction on emit.

* Add all the hashed string literals to ProgramLayout.

* Add reflection support for hashed string literals to reflection test.

* Fix string literal hash test.

* Small fixes to pass test suite.

* Fix issue in serialization where IRUse is not correctly initialized.

* Fix problem initializing IRUse for string hash pass.
Remove hack from slang-ir-specialize - specially handling if user is not null.

* * Use shared builder when replacing getStringHash
* Comments for functions in slang-ir-string-hash
* Do not allow zero length string literals. Could be allowed, but doing so would require StringSlicePool to have a special case (or some other mechanism)
---
 source/slang/slang-ir-string-hash.cpp | 108 ++++++++++++++++++++++++++++++++++
 1 file changed, 108 insertions(+)
 create mode 100644 source/slang/slang-ir-string-hash.cpp

(limited to 'source/slang/slang-ir-string-hash.cpp')

diff --git a/source/slang/slang-ir-string-hash.cpp b/source/slang/slang-ir-string-hash.cpp
new file mode 100644
index 000000000..b9e2d4045
--- /dev/null
+++ b/source/slang/slang-ir-string-hash.cpp
@@ -0,0 +1,108 @@
+// slang-ir-string-hash.cpp
+#include "slang-ir-string-hash.h"
+
+#include "slang-ir.h"
+#include "slang-ir-insts.h"
+
+namespace Slang {
+
+static void _findGetStringHashRec(IRInst* inst, List<IRGetStringHash*>& outInsts)
+{
+    for (IRInst* child = inst->getFirstDecorationOrChild(); child; child = child->getNextInst())
+    {
+        if (IRGetStringHash* getInst = as<IRGetStringHash>(child))
+        {
+            outInsts.add(getInst);
+        }
+        _findGetStringHashRec(child, outInsts);
+    }
+}
+
+void replaceGetStringHash(IRModule* module, SharedIRBuilder& sharedBuilder, StringSlicePool& ioPool)
+{
+    IRBuilder builder;
+    builder.sharedBuilder = &sharedBuilder;
+
+    builder.setInsertInto(module->getModuleInst());
+
+    List<IRGetStringHash*> insts;
+    _findGetStringHashRec(module->getModuleInst(), insts);
+
+    // Then we want to add the GlobalHashedString instruction in the root
+    for (auto inst : insts)
+    {
+        IRStringLit* stringLit = inst->getStringLit();
+        ioPool.add(stringLit->getStringSlice());
+        
+        // Okay work out what the hash is
+        const int hash = GetHashCode(stringLit->getStringSlice());
+
+        IRInst* intLit = builder.getIntValue(builder.getIntType(), int32_t(hash));
+
+        // Okay we want to replace all uses with the literal
+        inst->replaceUsesWith(intLit);
+        inst->removeAndDeallocate();
+    }
+}
+
+void replaceGetStringHashWithGlobal(IRModule* module, SharedIRBuilder& sharedBuilder)
+{
+    StringSlicePool pool;
+    replaceGetStringHash(module, sharedBuilder, pool);
+    addGlobalHashedStringLiterals(pool, sharedBuilder);
+}
+
+void findGlobalHashedStringLiterals(IRModule* module, StringSlicePool& pool)
+{
+    IRModuleInst* moduleInst = module->getModuleInst();
+
+    for (IRInst* child = moduleInst->getFirstDecorationOrChild(); child; child = child->getNextInst())
+    {
+        if (IRGlobalHashedStringLiterals* hashedStringLits = as<IRGlobalHashedStringLiterals>(child))
+        {
+            const Index count = hashedStringLits->getOperandCount();
+            for (Index i = 0; i < count; ++i)
+            {
+                IRStringLit* stringLit = as<IRStringLit>(hashedStringLits->getOperand(i));
+                pool.add(stringLit->getStringSlice());
+            }
+        }
+    }
+}
+
+void addGlobalHashedStringLiterals(const StringSlicePool& pool, SharedIRBuilder& sharedBuilder)
+{
+    if (pool.getNumSlices() <= StringSlicePool::kNumDefaultHandles)
+    {
+        return;
+    }
+
+    IRBuilder builder;
+    builder.sharedBuilder = &sharedBuilder;
+    
+    // 
+    IRModule* module = builder.getModule();
+
+    // We need to add a global instruction that references all of these string literals
+    builder.setInsertInto(module->getModuleInst());
+
+    Index numSlices = Index(pool.getNumSlices() - StringSlicePool::kNumDefaultHandles);
+
+    IRInst* globalHashedInst = createEmptyInst(module, kIROp_GlobalHashedStringLiterals, int(numSlices));
+    builder.addInst(globalHashedInst);
+
+    auto operands = globalHashedInst->getOperands();
+
+    for (Index i = 0; i < numSlices; ++i)
+    {
+        UnownedStringSlice slice = pool.getSlice(StringSlicePool::Handle(i + StringSlicePool::kNumDefaultHandles));
+        IRStringLit* stringLit = builder.getStringValue(slice);
+
+        operands[i].init(globalHashedInst, stringLit);
+    }
+
+    // Mark to keep alive
+    builder.addKeepAliveDecoration(globalHashedInst);
+}
+
+}
-- 
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