glslang -> SPV: fix degenerate switch topologies (bug 14118).

git-svn-id: https://cvs.khronos.org/svn/repos/ogl/trunk/ecosystem/public/sdk/tools/glslang@31485 e7fa87d3-cd2b-0410-9028-fcbf551c1848

SPIRV/GlslangToSpv.cpp

@@ -1109,7 +1109,8 @@ bool TGlslangToSpvTraverser::visitSwitch(glslang::TVisit /* visit */, glslang::T
 
     // handle the case where the last code segment is missing, due to no code 
     // statements between the last case and the end of the switch statement
-    if ((int)codeSegments.size() == valueIndexToSegment[caseValues.size() - 1])
+    if ((caseValues.size() && (int)codeSegments.size() == valueIndexToSegment[caseValues.size() - 1]) ||
+        (int)codeSegments.size() == defaultSegment)
         codeSegments.push_back(nullptr);
 
     // make the switch statement

Test/baseResults/spv.switch.frag.out

@@ -1,5 +1,7 @@
 spv.switch.frag
 WARNING: 0:121: 'switch' : last case/default label not followed by statements 
+WARNING: 0:134: 'switch' : last case/default label not followed by statements 
+WARNING: 0:139: 'switch' : last case/default label not followed by statements 
 
 
 
@@ -9,7 +11,7 @@ Linked fragment stage:
 
 // Module Version 99
 // Generated by (magic number): 51a00bb
-// Id's are bound by 249
+// Id's are bound by 261
 
                               Source ESSL 300
                1:             ExtInstImport  "GLSL.std.450"
@@ -322,6 +324,21 @@ Linked fragment stage:
              247:    7(float) Load 222(color) 
              248:    7(float) FAdd 247 246
                               Store 222(color) 248 
+             249:     10(int) Load 61(c) 
+                              SelectionMerge 252 None
+                              Switch 249 251 
+                                     case 0: 250
+             250:               Label
+                                Branch 252
+             251:               Label
+                                Branch 252
+             252:             Label
+             256:     10(int) Load 61(c) 
+                              SelectionMerge 258 None
+                              Switch 256 257 
+             257:               Label
+                                Branch 258
+             258:             Label
                               Branch 6
                6:             Label
                               Return

Test/spv.switch.frag

@@ -130,4 +130,13 @@ void main()
 
     color += foo1(v,v,c).y;
     color += foo2(v,v,c).z;
+
+    switch (c) {
+    case 0: break;
+    default:
+    }
+
+    switch (c) {
+    default:
+    }
 }