[Bug 99349] Failed to build shader (translation from TGSI)

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=99349

--- Comment #7 from Gert Wollny <gw.fossdev at gmail.com> ---
Now, just  multiplying two constants/uniforms not necessarily trigger the bug.
With a simple shader program like 

uniform vec4 base_color;
uniform vec4 test;
uniform vec4 test2;
uniform vec4 test3;

void main()
{
 vec4 h1 = base_color * test;
 vec4 h2 = test2 * test3;
 gl_FragColor = h1 * h2;
}

for both const-const multiplications one constant is always addressed via a
GPR, i.e. I get 

  1: MUL TEMP[0], CONST[0], CONST[1]
r600_shader.c:3986 tgsi_op2_s - About to multiply two constants
r600_shader.c:4000 tgsi_op2_s -  ctx->src[0]: 
                  sel:7   // this is a GPR address 
              swizzle:0 1 2 3
                  neg:0
                  abs:0
                  rel:0
              kc_bank:0
               kc_rel:0
                value:0 0 0 0

r600_shader.c:4000 tgsi_op2_s -  ctx->src[1]: 
                  sel:513  // this is a cfile address 
              swizzle:0 1 2 3
                  neg:0
                  abs:0
                  rel:0
              kc_bank:0
               kc_rel:0
                value:0 0 0 0

and then check_vector/reserve_cfile can successfully assign the read ports via
cfile because only 4 values need to be read. 


However, for a more complicated shader I get the following:  

250: MUL TEMP[11], CONST[26], CONST[23]
r600_shader.c:3986 tgsi_op2_s - About to multiply two constants
r600_shader.c:4000 tgsi_op2_s -  ctx->src[0]: 
                  sel:160  // cfile kcache after  translation 
              swizzle:0 1 2 3
                  neg:0
                  abs:0
                  rel:0
              kc_bank:0
               kc_rel:0
                value:0 0 0 0

r600_shader.c:4000 tgsi_op2_s -  ctx->src[1]: 
                  sel:535 // cfile kcache before  translation 
              swizzle:0 1 2 3
                  neg:0
                  abs:0
                  rel:0
              kc_bank:0
               kc_rel:0
                value:0 0 0 0

r600_asm.c:472 check_vector -  bs->hw_cfile_addr:[-1 -1]  bs->hw_cfile_elem:
[-1 -1] bank_swizzle:0  num_src:2
r600_asm.c:494 check_vector -  src 0: sel:160 elem:0
r600_asm.c:423 reserve_cfile -   res=0: bs->hw_cfile_addr:-1
bs->hw_cfile_elem:-1 sel:160 chan:0
r600_asm.c:494 check_vector -  src 1: sel:535 elem:0
r600_asm.c:423 reserve_cfile -   res=0: bs->hw_cfile_addr:160
bs->hw_cfile_elem:0 sel:535 chan:0
r600_asm.c:423 reserve_cfile -   res=1: bs->hw_cfile_addr:-1
bs->hw_cfile_elem:-1 sel:535 chan:0
r600_asm.c:472 check_vector -  bs->hw_cfile_addr:[160 535]  bs->hw_cfile_elem:
[0 0] bank_swizzle:0  num_src:2
r600_asm.c:494 check_vector -  src 0: sel:160 elem:1
r600_asm.c:423 reserve_cfile -   res=0: bs->hw_cfile_addr:160
bs->hw_cfile_elem:0 sel:160 chan:0
r600_asm.c:494 check_vector -  src 1: sel:535 elem:1
r600_asm.c:423 reserve_cfile -   res=0: bs->hw_cfile_addr:160
bs->hw_cfile_elem:0 sel:535 chan:0
r600_asm.c:423 reserve_cfile -   res=1: bs->hw_cfile_addr:535
bs->hw_cfile_elem:0 sel:535 chan:0
r600_asm.c:472 check_vector -  bs->hw_cfile_addr:[160 535]  bs->hw_cfile_elem:
[0 0] bank_swizzle:0  num_src:2
r600_asm.c:494 check_vector -  src 0: sel:160 elem:2
r600_asm.c:423 reserve_cfile -   res=0: bs->hw_cfile_addr:160
bs->hw_cfile_elem:0 sel:160 chan:1
r600_asm.c:423 reserve_cfile -   res=1: bs->hw_cfile_addr:535
bs->hw_cfile_elem:0 sel:160 chan:1
r600_asm.c:436 reserve_cfile - All cfile read ports are used, cannot reference
vector element.

In summary allocating a read port for elem >= 2 fails, because it would mean
reading more than four values in one instruction group, and this is ot possible
according to the AMD Evergreen-Family instruction set manual 4.7.5.

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