From: Marek Olšák <marek.ol...@amd.com>
See my LLVM patch which fixes the root cause.
Users have to apply this patch and then they have 2 choices:
- Downgrade to LLVM 5.0
- Update to LLVM git after my LLVM patch is pushed.
It won't be possible to use current and earlier development version
of LLVM 6.0.
---
src/gallium/drivers/radeonsi/si_shader.c | 13 ++++++++++---
1 file changed, 10 insertions(+), 3 deletions(-)
diff --git a/src/gallium/drivers/radeonsi/si_shader.c
b/src/gallium/drivers/radeonsi/si_shader.c
index 1320c6f..a248cea 100644
--- a/src/gallium/drivers/radeonsi/si_shader.c
+++ b/src/gallium/drivers/radeonsi/si_shader.c
@@ -2008,28 +2008,35 @@ static LLVMValueRef fetch_constant(
if (sel->info.const_buffers_declared == 1 &&
sel->info.shader_buffers_declared == 0) {
LLVMValueRef ptr =
LLVMGetParam(ctx->main_fn,
ctx->param_const_and_shader_buffers);
/* This enables use of s_load_dword and flat_load_dword for
const buffer 0
* loads, and up to x4 load opcode merging. However, it leads
to horrible
* code reducing SIMD wave occupancy from 8 to 2 in many cases.
*
* Using s_buffer_load_dword (x1) seems to be the best option
right now.
+ *
+ * LLVM 5.0 on SI doesn't insert a required s_nop between SALU
setting
+ * a descriptor and s_buffer_load_dword using it, so we can't
expand
+ * the pointer into a full descriptor like below. We have to use
+ * s_load_dword instead. The only case when LLVM 5.0 would
select
+ * s_buffer_load_dword (that we have to prevent) is when we use
use
+ * a literal offset where we don't need bounds checking.
*/
-#if 0 /* keep this codepath disabled */
- if (!reg->Register.Indirect) {
+ if (ctx->screen->b.chip_class == SI &&
+ HAVE_LLVM < 0x0600 &&
+ !reg->Register.Indirect) {
addr = LLVMBuildLShr(ctx->ac.builder, addr,
LLVMConstInt(ctx->i32, 2, 0), "");
LLVMValueRef result = ac_build_load_invariant(&ctx->ac,
ptr, addr);
return bitcast(bld_base, type, result);
}
-#endif
/* Do the bounds checking with a descriptor, because
* doing computation and manual bounds checking of 64-bit
* addresses generates horrible VALU code with very high
* VGPR usage and very low SIMD occupancy.
*/
ptr = LLVMBuildPtrToInt(ctx->ac.builder, ptr, ctx->i64, "");
ptr = LLVMBuildBitCast(ctx->ac.builder, ptr, ctx->v2i32, "");
LLVMValueRef desc_elems[] = {
--
2.7.4
_______________________________________________
mesa-dev mailing list
mesa-dev@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/mesa-dev
