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

diff --git a/src/gallium/drivers/r600/r600_asm.c b/src/gallium/drivers/r600/r600_asm.c
index bc69806..ee7beee 100644 (file)
--- 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 (file)
--- 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 (file)
--- 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;
                }