r600g: Fix special negative immediate constants when using ABS modifier.

Some constants (like 1.0 and 0.5) could be inlined as immediate inputs
without using their literal value. The r600_bytecode_special_constants()
function emulates the negative of these constants by using NEG modifier.

However some shaders define -1.0 constant and want to use it as 1.0.
They do so by using ABS modifier. But r600_bytecode_special_constants()
set NEG in addition to ABS. Since NEG modifier have priority over ABS one,
we get -|1.0| as result, instead of |1.0|.

The patch simply prevents the additional switching of NEG when ABS is set.

[According to Ivan Kalvachev, this bug was fond via
https://github.com/iXit/Mesa-3D/issues/126 and
https://github.com/iXit/Mesa-3D/issues/127]

Signed-off-by: Ivan Kalvachev <[email protected]>
Reviewed-by: Nicolai Hähnle <[email protected]>
CC: <[email protected]>

1 files changed, 4 insertions, 4 deletions

diff --git a/src/gallium/drivers/r600/r600_asm.c b/src/gallium/drivers/r600/r600_asm.c
index bc6980660a5..ee7beee3001 100644
--- a/src/gallium/drivers/r600/r600_asm.c
+++ b/src/gallium/drivers/r600/r600_asm.c
@@ -635,7 +635,7 @@ static int replace_gpr_with_pv_ps(struct r600_bytecode *bc,
 	return 0;
 }
 
-void r600_bytecode_special_constants(uint32_t value, unsigned *sel, unsigned *neg)
+void r600_bytecode_special_constants(uint32_t value, unsigned *sel, unsigned *neg, unsigned abs)
 {
 	switch(value) {
 	case 0:
@@ -655,11 +655,11 @@ void r600_bytecode_special_constants(uint32_t value, unsigned *sel, unsigned *ne
 		break;
 	case 0xBF800000: /* -1.0f */
 		*sel = V_SQ_ALU_SRC_1;
-		*neg ^= 1;
+		*neg ^= !abs;
 		break;
 	case 0xBF000000: /* -0.5f */
 		*sel = V_SQ_ALU_SRC_0_5;
-		*neg ^= 1;
+		*neg ^= !abs;
 		break;
 	default:
 		*sel = V_SQ_ALU_SRC_LITERAL;
@@ -1208,7 +1208,7 @@ int r600_bytecode_add_alu_type(struct r600_bytecode *bc,
 		}
 		if (nalu->src[i].sel == V_SQ_ALU_SRC_LITERAL)
 			r600_bytecode_special_constants(nalu->src[i].value,
-				&nalu->src[i].sel, &nalu->src[i].neg);
+				&nalu->src[i].sel, &nalu->src[i].neg, nalu->src[i].abs);
 	}
 	if (nalu->dst.sel >= bc->ngpr) {
 		bc->ngpr = nalu->dst.sel + 1;