Remove shader call stack bounding

The root cause of a shader call stack overflow was fixed in
https://swiftshader-review.googlesource.com/c/SwiftShader/+/24628
All shaders should now be validated not to exceed our call stack size
before reaching this lowering stage of compilation. Thus the run-time
checks can be removed.

This partially reverts
https://swiftshader-review.googlesource.com/c/SwiftShader/+/23568

Bug b/123587120

Change-Id: I04fc2613da7526992dd52c323deca8d9ad2c30c0
Reviewed-on: https://swiftshader-review.googlesource.com/c/24648
Kokoro-Presubmit: kokoro <noreply+kokoro@google.com>
Tested-by: Nicolas Capens <nicolascapens@google.com>
Reviewed-by: Alexis Hétu <sugoi@google.com>

src/Shader/PixelProgram.cpp

diff --git a/src/Shader/PixelProgram.cpp b/src/Shader/PixelProgram.cpp
index bc879a3..ca44d19 100644
--- a/src/Shader/PixelProgram.cpp
+++ b/src/Shader/PixelProgram.cpp
@@ -1419,7 +1419,7 @@
 
 		if(callRetBlock[labelIndex].size() > 1)
 		{
-			callStack[Min(stackIndex++, Int(MAX_SHADER_CALL_STACK_SIZE))] = UInt(callSiteIndex);
+			callStack[stackIndex++] = UInt(callSiteIndex);
 		}
 
 		Int4 restoreLeave = enableLeave;
@@ -1459,7 +1459,7 @@
 
 		if(callRetBlock[labelIndex].size() > 1)
 		{
-			callStack[Min(stackIndex++, Int(MAX_SHADER_CALL_STACK_SIZE))] = UInt(callSiteIndex);
+			callStack[stackIndex++] = UInt(callSiteIndex);
 		}
 
 		Int4 restoreLeave = enableLeave;
@@ -1488,7 +1488,7 @@
 
 		if(callRetBlock[labelIndex].size() > 1)
 		{
-			callStack[Min(stackIndex++, Int(MAX_SHADER_CALL_STACK_SIZE))] = UInt(callSiteIndex);
+			callStack[stackIndex++] = UInt(callSiteIndex);
 		}
 
 		enableIndex++;

src/Shader/VertexProgram.cpp

diff --git a/src/Shader/VertexProgram.cpp b/src/Shader/VertexProgram.cpp
index 05f8dfb..8bae9cf 100644
--- a/src/Shader/VertexProgram.cpp
+++ b/src/Shader/VertexProgram.cpp
@@ -1124,7 +1124,7 @@
 
 		if(callRetBlock[labelIndex].size() > 1)
 		{
-			callStack[Min(stackIndex++, Int(MAX_SHADER_CALL_STACK_SIZE))] = UInt(callSiteIndex);
+			callStack[stackIndex++] = UInt(callSiteIndex);
 		}
 
 		Int4 restoreLeave = enableLeave;
@@ -1164,7 +1164,7 @@
 
 		if(callRetBlock[labelIndex].size() > 1)
 		{
-			callStack[Min(stackIndex++, Int(MAX_SHADER_CALL_STACK_SIZE))] = UInt(callSiteIndex);
+			callStack[stackIndex++] = UInt(callSiteIndex);
 		}
 
 		Int4 restoreLeave = enableLeave;
@@ -1193,7 +1193,7 @@
 
 		if(callRetBlock[labelIndex].size() > 1)
 		{
-			callStack[Min(stackIndex++, Int(MAX_SHADER_CALL_STACK_SIZE))] = UInt(callSiteIndex);
+			callStack[stackIndex++] = UInt(callSiteIndex);
 		}
 
 		enableIndex++;