Tint/transform: Fix insertBits polyfill for HLSL
This CL fix insertBits polyfill to handle with the left-shifting
behavior in HLSL, i.e. `(1u << 32u) == (1u << 0u) == 1u` where we want
the result to be `0u`.
Fixed: tint:1743
Change-Id: Ibb82abe4ab2f76dbb0fa06057fb19f15f961d969
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/108166
Commit-Queue: Zhaoming Jiang <zhaoming.jiang@intel.com>
Reviewed-by: Ben Clayton <bclayton@google.com>
Kokoro: Kokoro <noreply+kokoro@google.com>
diff --git a/test/tint/builtins/insertBits/vec3/u32.spvasm.expected.fxc.hlsl b/test/tint/builtins/insertBits/vec3/u32.spvasm.expected.fxc.hlsl
index ebd4fb3..a778070 100644
--- a/test/tint/builtins/insertBits/vec3/u32.spvasm.expected.fxc.hlsl
+++ b/test/tint/builtins/insertBits/vec3/u32.spvasm.expected.fxc.hlsl
@@ -1,8 +1,7 @@
uint3 tint_insert_bits(uint3 v, uint3 n, uint offset, uint count) {
- const uint s = min(offset, 32u);
- const uint e = min(32u, (s + count));
- const uint mask = (((1u << s) - 1u) ^ ((1u << e) - 1u));
- return (((n << uint3((s).xxx)) & uint3((mask).xxx)) | (v & uint3((~(mask)).xxx)));
+ const uint e = (offset + count);
+ const uint mask = ((((offset < 32u) ? (1u << offset) : 0u) - 1u) ^ (((e < 32u) ? (1u << e) : 0u) - 1u));
+ return ((((offset < 32u) ? (n << uint3((offset).xxx)) : (0u).xxx) & uint3((mask).xxx)) | (v & uint3((~(mask)).xxx)));
}
void f_1() {
