Fix assert on using GLSL sampler function arguments.

Bug b/31651425

Change-Id: Ic6c1f16b1ec3ef039e15e72e70a1daee711fba2f
Reviewed-on: https://swiftshader-review.googlesource.com/9748
Reviewed-by: Alexis Hétu <sugoi@google.com>
Reviewed-by: Nicolas Capens <capn@google.com>
Tested-by: Nicolas Capens <capn@google.com>

src/OpenGL/compiler/OutputASM.cpp

diff --git a/src/OpenGL/compiler/OutputASM.cpp b/src/OpenGL/compiler/OutputASM.cpp
index 49f62b1..a0b5500 100644
--- a/src/OpenGL/compiler/OutputASM.cpp
+++ b/src/OpenGL/compiler/OutputASM.cpp
@@ -2944,9 +2944,19 @@
 		TIntermSymbol *symbol = sampler->getAsSymbolNode();
 		TIntermBinary *binary = sampler->getAsBinaryNode();
 
-		if(symbol && type.getQualifier() == EvqUniform)
+		if(symbol)
 		{
-			return samplerRegister(symbol);
+			switch(type.getQualifier())
+			{
+			case EvqUniform:
+				return samplerRegister(symbol);
+			case EvqIn:
+			case EvqConstReadOnly:
+				// Function arguments are not (uniform) sampler registers
+				return -1;
+			default:
+				UNREACHABLE(type.getQualifier());
+			}
 		}
 		else if(binary)
 		{
@@ -2992,7 +3002,7 @@
 		}
 
 		UNREACHABLE(0);
-		return -1;   // Not a sampler register
+		return -1;   // Not a (uniform) sampler register
 	}
 
 	int OutputASM::samplerRegister(TIntermSymbol *sampler)