Add fwidth_coarse and fwidth_fine functions (#6941)

Fixes #6940.

Add new Slang fwidth_coarse and fwidth_fine functions, similar to GLSL's fwidthCoarse and fwidthFine.
Move the implementation of the GLSL functions from glsl.meta.slang to hlsl.meta.slang.

Update the existing spirv/fwidth.slang test with the new functions, and add a new hlsl-intrinsic/fragment-derivative.slang test to test HLSL, SPIR-V, and GLSL targets for the new functions.

1 files changed, 35 insertions, 19 deletions

diff --git a/tests/spirv/fwidth.slang b/tests/spirv/fwidth.slang
index a55dfa3b0..a65e799f5 100644
--- a/tests/spirv/fwidth.slang
+++ b/tests/spirv/fwidth.slang
@@ -17,50 +17,66 @@ void main()
         float b2 = ddy(w);
         output[2] = b2;
 
-        // CHECK: OpDPdxCoarse
-        float b3 = ddx_coarse(w);
+        // CHECK: OpFwidthCoarse
+        float b3 = fwidth_coarse(w);
         output[3] = b3;
 
-        // CHECK: OpDPdyCoarse
-        float b4 = ddy_coarse(w);
+        // CHECK: OpDPdxCoarse
+        float b4 = ddx_coarse(w);
         output[4] = b4;
 
-        // CHECK: OpDPdxFine
-        float b5 = ddx_fine(w);
+        // CHECK: OpDPdyCoarse
+        float b5 = ddy_coarse(w);
         output[5] = b5;
 
-        // CHECK: OpDPdyFine
-        float b6 = ddy_fine(w);
+        // CHECK: OpFwidthFine
+        float b6 = fwidth_fine(w);
         output[6] = b6;
+
+        // CHECK: OpDPdxFine
+        float b7 = ddx_fine(w);
+        output[7] = b7;
+
+        // CHECK: OpDPdyFine
+        float b8 = ddy_fine(w);
+        output[8] = b8;
     }
 
     {
         // CHECK: OpFwidth
         float3 w = 1.0;
         float3 b = fwidth(w);
-        output[7] = b.x;
+        output[9] = b.x;
 
         // CHECK: OpDPdx
         float3 b1 = ddx(w);
-        output[8] = b1.x;
+        output[10] = b1.x;
         // CHECK: OpDPdy
         float3 b2 = ddy(w);
-        output[9] = b2.x;
+        output[11] = b2.x;
+
+        // CHECK: OpFwidthCoarse
+        float3 b3 = fwidth_coarse(w);
+        output[12] = b3.x;
 
         // CHECK: OpDPdxCoarse
-        float3 b3 = ddx_coarse(w);
-        output[10] = b3.x;
+        float3 b4 = ddx_coarse(w);
+        output[13] = b4.x;
 
         // CHECK: OpDPdyCoarse
-        float3 b4 = ddy_coarse(w);
-        output[11] = b4.x;
+        float3 b5 = ddy_coarse(w);
+        output[14] = b5.x;
+
+        // CHECK: OpFwidthFine
+        float3 b6 = fwidth_fine(w);
+        output[15] = b6.x;
 
         // CHECK: OpDPdxFine
-        float3 b5 = ddx_fine(w);
-        output[12] = b5.x;
+        float3 b7 = ddx_fine(w);
+        output[16] = b7.x;
 
         // CHECK: OpDPdyFine
-        float3 b6 = ddy_fine(w);
-        output[13] = b6.x;
+        float3 b8 = ddy_fine(w);
+        output[17] = b8.x;
     }
 }