nir: Add support for 1-bit data types

This commit adds support for 1-bit Booleans and integers.  Booleans
obviously take a value of true or false.  Because we have to define the
semantics of 1-bit signed and unsigned integers, we define uint1_t to
take values of 0 and 1 and int1_t to take values of 0 and -1.  1-bit
arithmetic is then well-defined in the usual way, just with fewer bits.
The definition of int1_t and uint1_t doesn't usually matter but we do
need something for purposes of constant folding.

Reviewed-by: Eric Anholt <[email protected]>
Reviewed-by: Bas Nieuwenhuizen <[email protected]>
Tested-by: Bas Nieuwenhuizen <[email protected]>

1 files changed, 11 insertions, 1 deletions

diff --git a/src/compiler/nir/nir_builder.h b/src/compiler/nir/nir_builder.h
index e0cdcd4ba23..d8abb7fd027 100644
--- a/src/compiler/nir/nir_builder.h
+++ b/src/compiler/nir/nir_builder.h
@@ -332,7 +332,10 @@ nir_imm_intN_t(nir_builder *build, uint64_t x, unsigned bit_size)
 
    memset(&v, 0, sizeof(v));
    assert(bit_size <= 64);
-   v.i64[0] = x & (~0ull >> (64 - bit_size));
+   if (bit_size == 1)
+      v.b[0] = x & 1;
+   else
+      v.i64[0] = x & (~0ull >> (64 - bit_size));
 
    return nir_build_imm(build, 1, bit_size, v);
 }
@@ -352,6 +355,13 @@ nir_imm_ivec4(nir_builder *build, int x, int y, int z, int w)
 }
 
 static inline nir_ssa_def *
+nir_imm_boolN_t(nir_builder *build, bool x, unsigned bit_size)
+{
+   /* We use a 0/-1 convention for all booleans regardless of size */
+   return nir_imm_intN_t(build, -(int)x, bit_size);
+}
+
+static inline nir_ssa_def *
 nir_build_alu(nir_builder *build, nir_op op, nir_ssa_def *src0,
               nir_ssa_def *src1, nir_ssa_def *src2, nir_ssa_def *src3)
 {