Disable warnings for input global variables (shader-slang#4745)

* Disable warnings for input global variables

* Update comment to reflect actual check

Co-authored-by: ArielG-NV <159081215+ArielG-NV@users.noreply.github.com>

* Update comments in uninitialized-globals.slang

* Update uninitialized-globals.slang

* Refactoring test variable

* Typo in test

---------

Co-authored-by: ArielG-NV <159081215+ArielG-NV@users.noreply.github.com>

Author: venkataram-nv

source/slang/slang-ir-inst-defs.h

@@ -903,7 +903,7 @@ INST_RANGE(BindingQuery, GetRegisterIndex, GetRegisterSpace)
     INST(AlwaysFoldIntoUseSiteDecoration, alwaysFold, 0, 0)
 
     INST(GlobalOutputDecoration, output, 0, 0)
-    INST(GlobalInputDecoration, output, 0, 0)
+    INST(GlobalInputDecoration, input, 0, 0)
     INST(GLSLLocationDecoration, glslLocation, 1, 0)
     INST(GLSLOffsetDecoration, glslOffset, 1, 0)
     INST(PayloadDecoration, payload, 0, 0)

source/slang/slang-ir-use-uninitialized-values.cpp

@@ -552,6 +552,9 @@ namespace Slang
         if (variable->findDecoration<IRSemanticDecoration>())
             return;
 
+        if (variable->findDecoration<IRGlobalInputDecoration>())
+            return;
+
         // Check for initialization blocks
         for (auto inst : variable->getChildren())
         {

tests/diagnostics/uninitialized-globals.slang

@@ -1,8 +1,8 @@
-//TEST:SIMPLE(filecheck=CHK): -target spirv
+//TEST:SIMPLE(filecheck=CHK): -allow-glsl -target spirv
 
 // Using groupshared variables
 groupshared float4 gsConstexpr = float4(1.0f);
-groupshared float4 gsUndefined;
+groupshared float4 gsUninitialized;
 
 // OK
 float use_constexpr_initialized_gs()
@@ -12,8 +12,8 @@ float use_constexpr_initialized_gs()
 
 float use_undefined_gs()
 {
-    //CHK-DAG: warning 41017: use of uninitialized global variable 'gsUndefined'
-    return gsUndefined.x;
+    //CHK-DAG: ([[# @LINE + 1]]): warning 41017: use of uninitialized global variable 'gsUninitialized'
+    return gsUninitialized.x;
 }
 
 // Using static variables
@@ -35,7 +35,7 @@ void write_to_later()
 
 float use_never_written()
 {
-    //CHK-DAG: warning 41017: use of uninitialized global variable 'writtenNever'
+    //CHK-DAG: ([[# @LINE + 1]]): warning 41017: use of uninitialized global variable 'writtenNever'
     return writtenNever;
 }
 
@@ -45,4 +45,35 @@ float use_later_writte()
     return writtenLater;
 }
 
+// Varying inputs never warn
+layout(location = 0) in vec4 data;
+
+vec4 glsl_layout_in_ok()
+{
+    return data;
+}
+
+// Layout outputs should still be written to at some point
+layout(location = 1) out vec4 x;
+
+vec4 glsl_layout_out_undefined()
+{
+    //CHK-DAG: ([[# @LINE + 1]]): warning 41017: use of uninitialized global variable 'x'
+    return x;
+}
+
+layout(location = 2) out vec4 y;
+
+void glsl_layout_out_store(vec4 data)
+{
+    // Written to here...
+    y = data;
+}
+
+vec4 glsl_layout_out_ok()
+{
+    // ...so read here is treated as OK
+    return y;
+}
+
 //CHK-NOT: warning 41017