Support for infinite literal of from 34.2432#INF (shader-slang#2944)

prelude/slang-cpp-prelude.h

@@ -43,6 +43,11 @@
 #define SLANG_PRELUDE_EXPORT_START SLANG_PRELUDE_EXTERN_C_START SLANG_PRELUDE_SHARED_LIB_EXPORT
 #define SLANG_PRELUDE_EXPORT_END SLANG_PRELUDE_EXTERN_C_END
 
+#ifndef INFINITY
+// Must overflow for double
+#   define INFINITY float(1e+300 * 1e+300)
+#endif
+
 #ifndef SLANG_INFINITY
 #   define SLANG_INFINITY   INFINITY
 #endif

source/compiler-core/slang-lexer.cpp

@@ -438,6 +438,22 @@ namespace Slang
 
     static bool _maybeLexNumberExponent(Lexer* lexer, int base)
     {
+        if (_peek(lexer) == '#')
+        {
+            // Special case #INF 
+            const auto inf = toSlice("#INF");
+            for (auto c : inf)
+            {
+                if (_peek(lexer) != c)
+                {
+                    return false;
+                }
+                _advance(lexer);
+            }
+
+            return true;
+        }
+
         if(!_isNumberExponent(_peek(lexer), base))
             return false;
 
@@ -626,6 +642,24 @@ namespace Slang
             }
         }
 
+        if (*cursor == '#')
+        {
+            // It must be INF
+            const auto inf = toSlice("#INF");
+
+            if (UnownedStringSlice(cursor, end).startsWith(inf))
+            {
+                if(outSuffix)
+                {
+                    *outSuffix = UnownedStringSlice(cursor + inf.getLength(), end);
+                }
+
+                value = INFINITY;
+
+                return value;
+            }
+        }
+
         // Now read optional exponent
         if(_isNumberExponent(*cursor, radix))
         {

tests/bugs/inf-float-literal.slang

@@ -0,0 +1,26 @@
+//TEST(compute):COMPARE_COMPUTE_EX:-slang -compute -shaderobj
+//TEST(compute,vulkan):COMPARE_COMPUTE_EX:-vk -slang -compute -shaderobj
+//TEST(compute):COMPARE_COMPUTE_EX:-cpu -slang -compute -shaderobj
+
+
+//TEST_INPUT:ubuffer(data=[0 0 0 0], stride=4):out,name outputBuffer
+RWStructuredBuffer<float> outputBuffer;
+
+[numthreads(4, 1, 1)]
+void computeMain(uint3 dispatchThreadID : SV_DispatchThreadID)
+{
+    int idx = int(dispatchThreadID.x);
+
+    float a;
+
+    switch (idx)
+    {
+        default:
+        case 0:     a = 1.#INF; break;
+        case 1:     a = 2.4#INFf; break;
+        case 2:     a = float(234.5#INFl); break;
+        case 3:     a = -1.#INF; break;
+    }
+
+    outputBuffer[idx] = a;
+}

tests/bugs/inf-float-literal.slang.expected.txt

@@ -0,0 +1,4 @@
+7F800000
+7F800000
+7F800000
+FF800000