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authorMatt Turner <[email protected]>2015-05-14 22:23:22 -0700
committerMatt Turner <[email protected]>2015-05-18 10:11:36 -0700
commit81deefc45ba7b7d3b2b5e7ccf9e1680df6e31e3a (patch)
tree7c09baa4660f8379d6084a03d7cac6c2accaff3b /src/mesa/drivers/dri
parent1e4e17fbd9296cc5064aabdb351a894d10190cb6 (diff)
i965/fs: Unrestrict constant propagation into integer multiply.
Gen8+'s MUL instruction doesn't ignore the high 16-bits of one source like on earlier platforms, so we can constant propagate into it without worry. Integer multiplies (not into the accumulator, which is done for imul_high) are lowered in lower_integer_multiplication(), so it's safe there as well. On Broadwell, fragment shaders only: total instructions in shared programs: 4377769 -> 4377451 (-0.01%) instructions in affected programs: 48064 -> 47746 (-0.66%) helped: 156 On Broadwell, vertex shaders only: total instructions in shared programs: 2858885 -> 2856313 (-0.09%) instructions in affected programs: 26380 -> 23808 (-9.75%) helped: 134 On Broadwell, vertex shaders only (with INTEL_USE_NIR=1): total instructions in shared programs: 2911688 -> 2865984 (-1.57%) instructions in affected programs: 1421715 -> 1376011 (-3.21%) helped: 6186 Reviewed-by: Jason Ekstrand <[email protected]>
Diffstat (limited to 'src/mesa/drivers/dri')
-rw-r--r--src/mesa/drivers/dri/i965/brw_fs_copy_propagation.cpp10
1 files changed, 9 insertions, 1 deletions
diff --git a/src/mesa/drivers/dri/i965/brw_fs_copy_propagation.cpp b/src/mesa/drivers/dri/i965/brw_fs_copy_propagation.cpp
index 52bfa921dc3..c92aae4b1d6 100644
--- a/src/mesa/drivers/dri/i965/brw_fs_copy_propagation.cpp
+++ b/src/mesa/drivers/dri/i965/brw_fs_copy_propagation.cpp
@@ -541,8 +541,16 @@ fs_visitor::try_constant_propagate(fs_inst *inst, acp_entry *entry)
/* Fit this constant in by commuting the operands.
* Exception: we can't do this for 32-bit integer MUL/MACH
* because it's asymmetric.
+ *
+ * The BSpec says for Broadwell that
+ *
+ * "When multiplying DW x DW, the dst cannot be accumulator."
+ *
+ * Integer MUL with a non-accumulator destination will be lowered
+ * by lower_integer_multiplication(), so don't restrict it.
*/
- if ((inst->opcode == BRW_OPCODE_MUL ||
+ if (((inst->opcode == BRW_OPCODE_MUL &&
+ inst->dst.is_accumulator()) ||
inst->opcode == BRW_OPCODE_MACH) &&
(inst->src[1].type == BRW_REGISTER_TYPE_D ||
inst->src[1].type == BRW_REGISTER_TYPE_UD))