wgsl: update find msb/lsb names (#1735)

CHANGELOG.md

@@ -5,6 +5,9 @@
     - attributes are declared with `@attrib` instead of `[[attrib]]`
     - `stride` attribute is removed
     - block comments are supported
+    - renames:
+      - `findLsb` -> `firstTrailingBit`
+      - `findMsb` -> `firstLeadingBit`
 
 ## v0.8 (2021-12-18)
   - development release for wgpu-0.12

src/back/wgsl/writer.rs

@@ -1527,8 +1527,8 @@ impl<W: Write> Writer<W> {
                     Mf::ReverseBits => Function::Regular("reverseBits"),
                     Mf::ExtractBits => Function::Regular("extractBits"),
                     Mf::InsertBits => Function::Regular("insertBits"),
-                    Mf::FindLsb => Function::Regular("findLsb"),
-                    Mf::FindMsb => Function::Regular("findMsb"),
+                    Mf::FindLsb => Function::Regular("firstTrailingBit"),
+                    Mf::FindMsb => Function::Regular("firstLeadingBit"),
                     // data packing
                     Mf::Pack4x8snorm => Function::Regular("pack4x8snorm"),
                     Mf::Pack4x8unorm => Function::Regular("pack4x8unorm"),

src/front/wgsl/conv.rs

@@ -201,8 +201,8 @@ pub fn map_standard_fun(word: &str) -> Option<crate::MathFunction> {
         "reverseBits" => Mf::ReverseBits,
         "extractBits" => Mf::ExtractBits,
         "insertBits" => Mf::InsertBits,
-        "findLsb" => Mf::FindLsb,
-        "findMsb" => Mf::FindMsb,
+        "firstTrailingBit" => Mf::FindLsb,
+        "firstLeadingBit" => Mf::FindMsb,
         // data packing
         "pack4x8snorm" => Mf::Pack4x8snorm,
         "pack4x8unorm" => Mf::Pack4x8unorm,

tests/in/bits.wgsl

@@ -36,8 +36,8 @@ fn main() {
     u2 = extractBits(u2, 5u, 10u);
     u3 = extractBits(u3, 5u, 10u);
     u4 = extractBits(u4, 5u, 10u);
-    i = findLsb(i);
-    i2 = findLsb(u2);
-    i3 = findMsb(i3);
-    i = findMsb(u);
+    i = firstTrailingBit(i);
+    i2 = firstTrailingBit(u2);
+    i3 = firstLeadingBit(i3);
+    i = firstLeadingBit(u);
 }

tests/out/wgsl/bits.wgsl

@@ -80,12 +80,12 @@ fn main() {
     let _e116 = u4_;
     u4_ = extractBits(_e116, 5u, 10u);
     let _e120 = i;
-    i = findLsb(_e120);
+    i = firstTrailingBit(_e120);
     let _e122 = u2_;
-    i2_ = findLsb(_e122);
+    i2_ = firstTrailingBit(_e122);
     let _e124 = i3_;
-    i3_ = findMsb(_e124);
+    i3_ = firstLeadingBit(_e124);
     let _e126 = u;
-    i = findMsb(_e126);
+    i = firstLeadingBit(_e126);
     return;
 }

tests/out/wgsl/bits_glsl-frag.wgsl

@@ -71,37 +71,37 @@ fn main_1() {
     let _e216 = u4_;
     u4_ = extractBits(_e216, u32(5), u32(10));
     let _e223 = i;
-    i = findLsb(_e223);
+    i = firstTrailingBit(_e223);
     let _e226 = i2_;
-    i2_ = findLsb(_e226);
+    i2_ = firstTrailingBit(_e226);
     let _e229 = i3_;
-    i3_ = findLsb(_e229);
+    i3_ = firstTrailingBit(_e229);
     let _e232 = i4_;
-    i4_ = findLsb(_e232);
+    i4_ = firstTrailingBit(_e232);
     let _e235 = u;
-    i = findLsb(_e235);
+    i = firstTrailingBit(_e235);
     let _e238 = u2_;
-    i2_ = findLsb(_e238);
+    i2_ = firstTrailingBit(_e238);
     let _e241 = u3_;
-    i3_ = findLsb(_e241);
+    i3_ = firstTrailingBit(_e241);
     let _e244 = u4_;
-    i4_ = findLsb(_e244);
+    i4_ = firstTrailingBit(_e244);
     let _e247 = i;
-    i = findMsb(_e247);
+    i = firstLeadingBit(_e247);
     let _e250 = i2_;
-    i2_ = findMsb(_e250);
+    i2_ = firstLeadingBit(_e250);
     let _e253 = i3_;
-    i3_ = findMsb(_e253);
+    i3_ = firstLeadingBit(_e253);
     let _e256 = i4_;
-    i4_ = findMsb(_e256);
+    i4_ = firstLeadingBit(_e256);
     let _e259 = u;
-    i = findMsb(_e259);
+    i = firstLeadingBit(_e259);
     let _e262 = u2_;
-    i2_ = findMsb(_e262);
+    i2_ = firstLeadingBit(_e262);
     let _e265 = u3_;
-    i3_ = findMsb(_e265);
+    i3_ = firstLeadingBit(_e265);
     let _e268 = u4_;
-    i4_ = findMsb(_e268);
+    i4_ = firstLeadingBit(_e268);
     return;
 }