From 99c295477fa1f6c5ce47e0d1c8fb3eea9d5e5f98 Mon Sep 17 00:00:00 2001
From: jsmall-nvidia <jsmall@nvidia.com>
Date: Thu, 7 Nov 2019 13:51:46 -0500
Subject: * Removed strip pass from emit as no longer needed (#1114)

* If obfuscate is enabled do strip on Layout
* Add option to keep insts that have layout decoration (else DCE strips layout)
* Add NameHint back in lowering - as strip now correctly removes. We may want NameHints in some stages even with obfuscation (for error messages in IR passes), as long as they are removed appropriately at the end
---
 source/slang/slang-emit.cpp        |  9 ---------
 source/slang/slang-ir-dce.cpp      |  5 +++++
 source/slang/slang-ir-dce.h        |  1 +
 source/slang/slang-lower-to-ir.cpp | 23 ++++++++++++++++++-----
 4 files changed, 24 insertions(+), 14 deletions(-)

(limited to 'source')

diff --git a/source/slang/slang-emit.cpp b/source/slang/slang-emit.cpp
index 670848002..345dfe9b2 100644
--- a/source/slang/slang-emit.cpp
+++ b/source/slang/slang-emit.cpp
@@ -474,15 +474,6 @@ String emitEntryPoint(
             break;
         }
 
-        // If we have obfuscation strip
-        if (compileRequest->getLinkage()->m_obfuscateCode)
-        {
-            IRStripOptions options;
-            options.shouldStripNameHints = true;
-            options.stripSourceLocs = true;
-            stripFrontEndOnlyInstructions(irModule, options);
-        }
-
         // The resource-based specialization pass above
         // may create specialized versions of functions, but
         // it does not try to completely eliminate the original
diff --git a/source/slang/slang-ir-dce.cpp b/source/slang/slang-ir-dce.cpp
index 4359e7e92..7c1cda75f 100644
--- a/source/slang/slang-ir-dce.cpp
+++ b/source/slang/slang-ir-dce.cpp
@@ -256,6 +256,11 @@ struct DeadCodeEliminationContext
             }
         }
 
+        if (options.keepLayoutsAlive && inst->findDecoration<IRLayoutDecoration>())
+        {
+            return true;
+        }
+
         // A basic block is an interesting case. Knowing that a function
         // is live means that its entry block is live, but the liveness
         // of any other blocks is determined by whether they are referenced
diff --git a/source/slang/slang-ir-dce.h b/source/slang/slang-ir-dce.h
index 6d4ae9d08..007905486 100644
--- a/source/slang/slang-ir-dce.h
+++ b/source/slang/slang-ir-dce.h
@@ -8,6 +8,7 @@ namespace Slang
     struct IRDeadCodeEliminationOptions
     {
         bool keepExportsAlive = false;
+        bool keepLayoutsAlive = false;
     };
 
         /// Eliminate "dead" code from the given IR module.
diff --git a/source/slang/slang-lower-to-ir.cpp b/source/slang/slang-lower-to-ir.cpp
index f9d39993a..93084fedd 100644
--- a/source/slang/slang-lower-to-ir.cpp
+++ b/source/slang/slang-lower-to-ir.cpp
@@ -1846,11 +1846,6 @@ static void addNameHint(
     IRInst*         inst,
     Decl*           decl)
 {
-    if (context->shared->m_obfuscateCode)
-    {
-        return;
-    }
-
     String name = getNameForNameHint(context, decl);
     if(name.getLength() == 0)
         return;
@@ -7294,6 +7289,24 @@ RefPtr<IRModule> TargetProgram::createIRModuleForLayout(DiagnosticSink* sink)
         builder->addLayoutDecoration(irType, irTypeLayout);
     }
 
+    // Lets strip and run DCE here
+    if (linkage->m_obfuscateCode)
+    {
+        IRStripOptions stripOptions;
+
+        stripOptions.shouldStripNameHints = linkage->m_obfuscateCode;
+        stripOptions.stripSourceLocs = linkage->m_obfuscateCode;
+
+        stripFrontEndOnlyInstructions(irModule, stripOptions);
+
+        IRDeadCodeEliminationOptions options;
+        options.keepExportsAlive = true;
+        options.keepLayoutsAlive = true;
+
+        // Eliminate any dead code
+        eliminateDeadCode(irModule, options);
+    }
+
     m_irModuleForLayout = irModule;
     return irModule;
 }
-- 
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