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Extract constant offsets from gather/scatter base+offsets offset vectors.

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When we're able to turn a general gather/scatter into the "base + offsets"
form, we now try to extract out any constant components of the offsets and
then pass them as a separate parameter to the gather/scatter function
implementation.

We then in turn carefully emit code for the addressing calculation so that
these constant offsets match LLVM's patterns to detect this case, such that
we get the constant offsets directly encoded in the instruction's addressing
calculation in many cases, saving arithmetic instructions to do these
calculations.

Improves performance of stencil by ~15%.  Other workloads unchanged.
This commit is contained in:
Matt Pharr
2012-01-24 14:41:15 -08:00
parent 7be2c399b1
commit a5b7fca7e0
5 changed files with 614 additions and 355 deletions
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8
builtins/target-generic-common.ll
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@@ -289,18 +289,18 @@ declare void @__masked_store_blend_64(<WIDTH x i64>* nocapture, <WIDTH x i64>,
define(`gather_scatter', `
declare <WIDTH x $1> @__gather_base_offsets32_$1(i8 * nocapture, <WIDTH x i32>,
i32, <WIDTH x i1>) nounwind readonly
i32, <WIDTH x i32>, <WIDTH x i1>) nounwind readonly
declare <WIDTH x $1> @__gather_base_offsets64_$1(i8 * nocapture, <WIDTH x i64>,
i32, <WIDTH x i1>) nounwind readonly
i32, <WIDTH x i64>, <WIDTH x i1>) nounwind readonly
declare <WIDTH x $1> @__gather32_$1(<WIDTH x i32>,
<WIDTH x i1>) nounwind readonly
declare <WIDTH x $1> @__gather64_$1(<WIDTH x i64>,
<WIDTH x i1>) nounwind readonly
declare void @__scatter_base_offsets32_$1(i8* nocapture, <WIDTH x i32>,
i32, <WIDTH x $1>, <WIDTH x i1>) nounwind
i32, <WIDTH x i32>, <WIDTH x $1>, <WIDTH x i1>) nounwind
declare void @__scatter_base_offsets64_$1(i8* nocapture, <WIDTH x i64>,
i32, <WIDTH x $1>, <WIDTH x i1>) nounwind
i32, <WIDTH x i64>, <WIDTH x $1>, <WIDTH x i1>) nounwind
declare void @__scatter32_$1(<WIDTH x i32>, <WIDTH x $1>,
<WIDTH x i1>) nounwind
declare void @__scatter64_$1(<WIDTH x i64>, <WIDTH x $1>,