Change for loops to use const refs, per performance-for-range-copy clang-tidy.

src/OpenGL/compiler/preprocessor/MacroExpander.cpp

@@ -83,11 +83,11 @@ MacroExpander::ScopedMacroReenabler::ScopedMacroReenabler(MacroExpander *expande
 MacroExpander::ScopedMacroReenabler::~ScopedMacroReenabler()
 {
 	mExpander->mDeferReenablingMacros = false;
-	for (auto macro : mExpander->mMacrosToReenable)
+	for (const auto &macro : mExpander->mMacrosToReenable)
 	{
 		// Copying the string here by using substr is a check for use-after-free. It detects
 		// use-after-free more reliably than just toggling the disabled flag.
-		assert(macro->name.substr() != "");
+		assert(!macro->name.substr().empty());
 		macro->disabled = false;
 	}
 	mExpander->mMacrosToReenable.clear();

src/Pipeline/SpirvShaderControlFlow.cpp

@@ -472,7 +472,7 @@ void SpirvShader::EmitLoop(EmitState *state) const
 	// Continue emitting from the merge block.
 	Nucleus::setInsertBlock(mergeBasicBlock);
 	state->pending->push_back(mergeBlockId);
-	for(auto it : mergeActiveLaneMasks)
+	for(const auto &it : mergeActiveLaneMasks)
 	{
 		state->addActiveLaneMaskEdge(it.first, mergeBlockId, it.second);
 	}
@@ -574,7 +574,7 @@ SpirvShader::EmitResult SpirvShader::EmitFunctionCall(InsnIterator insn, EmitSta
 	ASSERT(function.blocks.size() == 1);
 	spv::Op wrapOpKill[] = { spv::OpLabel, spv::OpKill };
 
-	for(auto block : function.blocks)
+	for(const auto &block : function.blocks)
 	{
 		int insnNumber = 0;
 		for(auto blockInsn : block.second)

src/Shader/Shader.cpp

@@ -2078,6 +2078,7 @@ namespace sw
 			}
 		}
 
+#if !defined(NDEBUG) || defined(DCHECK_ALWAYS_ON)
 		// Assert that every function is reachable (these should have been
 		// stripped in earlier stages). Unreachable functions may be code
 		// generated, but their own limits are not considered below, potentially
@@ -2085,7 +2086,8 @@ namespace sw
 		// If we ever find cases where there are unreachable functions, we can
 		// replace this assert with NO-OPing or stripping out the dead
 		// functions.
-		for (auto it : functions) { ASSERT(it.second.reachable); }
+		for (const auto &it : functions) { ASSERT(it.second.reachable); }
+#endif
 
 		// We have now gathered all the information about each of the functions
 		// in the shader. Traverse these functions starting from the main

third_party/subzero/src/IceTargetLoweringX8664Traits.h

@@ -679,7 +679,7 @@ public:
     RandomNumberGeneratorWrapper RNGW(RNG);
 
     // Shuffle the resulting equivalence classes.
-    for (auto I : EquivalenceClasses) {
+    for (const auto &I : EquivalenceClasses) {
       const RegisterList &List = I.second;
       RegisterList Shuffled(List);
       RandomShuffle(Shuffled.begin(), Shuffled.end(), RNGW);
@@ -695,7 +695,7 @@ public:
       OstreamLocker L(Func->getContext());
       Ostream &Str = Func->getContext()->getStrDump();
       Str << "Register equivalence classes:\n";
-      for (auto I : EquivalenceClasses) {
+      for (const auto &I : EquivalenceClasses) {
         Str << "{";
         const RegisterList &List = I.second;
         bool First = true;