Mesa (master): r600g: Fix special negative immediate constants when using ABS modifier.

[Nicolai Hähnle]

Module: Mesa
Branch: master
Commit: f75f21a24ae2dd83507f3d4d8007f0fcfe6db802
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=f75f21a24ae2dd83507f3d4d8007f0fcfe6db802

Author: Ivan Kalvachev <ikalvachev at gmail.com>
Date:   Sun Oct 25 01:16:58 2015 +0300

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 <ikalvachev at gmail.com>
Reviewed-by: Nicolai Hähnle <nicolai.haehnle at amd.com>
CC: <mesa-stable at lists.freedesktop.org>

---

 src/gallium/drivers/r600/r600_asm.c    |    8 ++++----
 src/gallium/drivers/r600/r600_asm.h    |    2 +-
 src/gallium/drivers/r600/r600_shader.c |    2 +-
 3 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/src/gallium/drivers/r600/r600_asm.c b/src/gallium/drivers/r600/r600_asm.c
index bc69806..ee7beee 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;
diff --git a/src/gallium/drivers/r600/r600_asm.h b/src/gallium/drivers/r600/r600_asm.h
index 7cf3a09..d48ad1e 100644
--- a/src/gallium/drivers/r600/r600_asm.h
+++ b/src/gallium/drivers/r600/r600_asm.h
@@ -255,7 +255,7 @@ int r600_bytecode_add_cfinst(struct r600_bytecode *bc,
 int r600_bytecode_add_alu_type(struct r600_bytecode *bc,
 		const struct r600_bytecode_alu *alu, unsigned type);
 void r600_bytecode_special_constants(uint32_t value,
-		unsigned *sel, unsigned *neg);
+		unsigned *sel, unsigned *neg, unsigned abs);
 void r600_bytecode_disasm(struct r600_bytecode *bc);
 void r600_bytecode_alu_read(struct r600_bytecode *bc,
 		struct r600_bytecode_alu *alu, uint32_t word0, uint32_t word1);
diff --git a/src/gallium/drivers/r600/r600_shader.c b/src/gallium/drivers/r600/r600_shader.c
index 8efe902..50c0329 100644
--- a/src/gallium/drivers/r600/r600_shader.c
+++ b/src/gallium/drivers/r600/r600_shader.c
@@ -1008,7 +1008,7 @@ static void tgsi_src(struct r600_shader_ctx *ctx,
 			(tgsi_src->Register.SwizzleX == tgsi_src->Register.SwizzleW)) {
 
 			index = tgsi_src->Register.Index * 4 + tgsi_src->Register.SwizzleX;
-			r600_bytecode_special_constants(ctx->literals[index], &r600_src->sel, &r600_src->neg);
+			r600_bytecode_special_constants(ctx->literals[index], &r600_src->sel, &r600_src->neg, r600_src->abs);
 			if (r600_src->sel != V_SQ_ALU_SRC_LITERAL)
 				return;
 		}