+/**
+ * Compute the swizzle obtained from the application of \p swz0 on the result
+ * of \p swz1. The argument ordering is expected to match function
+ * composition.
+ */
+static inline unsigned
+brw_compose_swizzle(unsigned swz0, unsigned swz1)
+{
+ return BRW_SWIZZLE4(
+ BRW_GET_SWZ(swz1, BRW_GET_SWZ(swz0, 0)),
+ BRW_GET_SWZ(swz1, BRW_GET_SWZ(swz0, 1)),
+ BRW_GET_SWZ(swz1, BRW_GET_SWZ(swz0, 2)),
+ BRW_GET_SWZ(swz1, BRW_GET_SWZ(swz0, 3)));
+}
+
+/**
+ * Return the result of applying swizzle \p swz to shuffle the bits of \p mask
+ * (AKA image).
+ */
+static inline unsigned
+brw_apply_swizzle_to_mask(unsigned swz, unsigned mask)
+{
+ unsigned result = 0;
+
+ for (unsigned i = 0; i < 4; i++) {
+ if (mask & (1 << BRW_GET_SWZ(swz, i)))
+ result |= 1 << i;
+ }
+
+ return result;
+}
+
+/**
+ * Return the result of applying the inverse of swizzle \p swz to shuffle the
+ * bits of \p mask (AKA preimage). Useful to find out which components are
+ * read from a swizzled source given the instruction writemask.
+ */
+static inline unsigned
+brw_apply_inv_swizzle_to_mask(unsigned swz, unsigned mask)
+{
+ unsigned result = 0;
+
+ for (unsigned i = 0; i < 4; i++) {
+ if (mask & (1 << i))
+ result |= 1 << BRW_GET_SWZ(swz, i);
+ }
+
+ return result;
+}
+
+/**
+ * Construct an identity swizzle for the set of enabled channels given by \p
+ * mask. The result will only reference channels enabled in the provided \p
+ * mask, assuming that \p mask is non-zero. The constructed swizzle will
+ * satisfy the property that for any instruction OP and any mask:
+ *
+ * brw_OP(p, brw_writemask(dst, mask),
+ * brw_swizzle(src, brw_swizzle_for_mask(mask)));
+ *
+ * will be equivalent to the same instruction without swizzle:
+ *
+ * brw_OP(p, brw_writemask(dst, mask), src);
+ */
+static inline unsigned
+brw_swizzle_for_mask(unsigned mask)
+{
+ unsigned last = (mask ? ffs(mask) - 1 : 0);
+ unsigned swz[4];
+
+ for (unsigned i = 0; i < 4; i++)
+ last = swz[i] = (mask & (1 << i) ? i : last);
+
+ return BRW_SWIZZLE4(swz[0], swz[1], swz[2], swz[3]);
+}
+
+/**
+ * Construct an identity swizzle for the first \p n components of a vector.
+ * When only a subset of channels of a vec4 are used we don't want to
+ * reference the other channels, as that will tell optimization passes that
+ * those other channels are used.
+ */
+static inline unsigned
+brw_swizzle_for_size(unsigned n)
+{
+ return brw_swizzle_for_mask((1 << n) - 1);
+}
+
+/**
+ * Converse of brw_swizzle_for_mask(). Returns the mask of components
+ * accessed by the specified swizzle \p swz.
+ */
+static inline unsigned
+brw_mask_for_swizzle(unsigned swz)
+{
+ return brw_apply_inv_swizzle_to_mask(swz, ~0);
+}
+
+enum PACKED brw_reg_type {
projects / mesa.git / blobdiff