llvm-project/llvm/test/CodeGen/PowerPC/vec_add_sub_doubleword.ll
Himadhith e4a4bb0f6d
[PowerPC] Replace vspltisw+vadduwm instructions with xxleqv+vsubuwm for adding the vector {1, 1, 1, 1} (#160882)
This patch optimizes vector addition operations involving **`all-ones`**
vectors by leveraging the generation of vectors of -1s(using `xxleqv`,
which is cheaper than generating vectors of 1s(`vspltisw`). These are
the respective vector types.
`v2i64`: **`A + vector {1, 1}`**
`v4i32`: **`A + vector {1, 1, 1, 1}`**
`v8i16`: **`A + vector {1, 1, 1, 1, 1, 1, 1, 1}`**
`v16i8`: **`A + vector {1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
1}`**

The optimized version replaces `vspltisw (4 cycles)` with `xxleqv (2
cycles)` using the following identity:
`A - (-1) = A + 1`.

---------

Co-authored-by: himadhith <himadhith.v@ibm.com>
Co-authored-by: Tony Varghese <tonypalampalliyil@gmail.com>
2025-11-21 12:26:58 +05:30

117 lines
3.5 KiB
LLVM

; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
; RUN: llc -verify-machineinstrs -mtriple=powerpc64-unknown-linux-gnu -mcpu=pwr8 < %s | FileCheck %s --check-prefixes=ALL,VSX
; RUN: llc -verify-machineinstrs -mtriple=powerpc64-unknown-linux-gnu -mcpu=pwr8 -mattr=-vsx < %s | FileCheck %s --check-prefixes=ALL,NOVSX
; Check VMX 64-bit integer operations
define <2 x i64> @test_add(<2 x i64> %x, <2 x i64> %y) nounwind {
; ALL-LABEL: test_add:
; ALL: # %bb.0:
; ALL-NEXT: vaddudm 2, 2, 3
; ALL-NEXT: blr
%result = add <2 x i64> %x, %y
ret <2 x i64> %result
}
define <2 x i64> @increment_by_one(<2 x i64> %x) nounwind {
; VSX-LABEL: increment_by_one:
; VSX: # %bb.0:
; VSX-NEXT: xxleqv 35, 35, 35
; VSX-NEXT: vsubudm 2, 2, 3
; VSX-NEXT: blr
;
; NOVSX-LABEL: increment_by_one:
; NOVSX: # %bb.0:
; NOVSX-NEXT: addis 3, 2, .LCPI1_0@toc@ha
; NOVSX-NEXT: addi 3, 3, .LCPI1_0@toc@l
; NOVSX-NEXT: lvx 3, 0, 3
; NOVSX-NEXT: vaddudm 2, 2, 3
; NOVSX-NEXT: blr
%result = add <2 x i64> %x, <i64 1, i64 1>
ret <2 x i64> %result
}
define <2 x i64> @increment_by_val(<2 x i64> %x, i64 %val) nounwind {
; VSX-LABEL: increment_by_val:
; VSX: # %bb.0:
; VSX-NEXT: mtfprd 0, 5
; VSX-NEXT: xxspltd 35, 0, 0
; VSX-NEXT: vaddudm 2, 2, 3
; VSX-NEXT: blr
;
; NOVSX-LABEL: increment_by_val:
; NOVSX: # %bb.0:
; NOVSX-NEXT: addi 3, 1, -16
; NOVSX-NEXT: std 5, -8(1)
; NOVSX-NEXT: std 5, -16(1)
; NOVSX-NEXT: lvx 3, 0, 3
; NOVSX-NEXT: vaddudm 2, 2, 3
; NOVSX-NEXT: blr
%tmpvec = insertelement <2 x i64> <i64 0, i64 0>, i64 %val, i32 0
%tmpvec2 = insertelement <2 x i64> %tmpvec, i64 %val, i32 1
%result = add <2 x i64> %x, %tmpvec2
ret <2 x i64> %result
; FIXME: This is currently generating the following instruction sequence
; std 5, -8(1)
; std 5, -16(1)
; addi 3, 1, -16
; ori 2, 2, 0
; lxvd2x 35, 0, 3
; vaddudm 2, 2, 3
; blr
; This will almost certainly cause a load-hit-store hazard.
; Since val is a value parameter, it should not need to be
; saved onto the stack at all (unless we're using this to set
; up the vector register). Instead, it would be better to splat
; the value into a vector register.
}
define <2 x i64> @test_sub(<2 x i64> %x, <2 x i64> %y) nounwind {
; ALL-LABEL: test_sub:
; ALL: # %bb.0:
; ALL-NEXT: vsubudm 2, 2, 3
; ALL-NEXT: blr
%result = sub <2 x i64> %x, %y
ret <2 x i64> %result
}
define <2 x i64> @decrement_by_one(<2 x i64> %x) nounwind {
; VSX-LABEL: decrement_by_one:
; VSX: # %bb.0:
; VSX-NEXT: xxleqv 35, 35, 35
; VSX-NEXT: vsubudm 2, 2, 3
; VSX-NEXT: blr
;
; NOVSX-LABEL: decrement_by_one:
; NOVSX: # %bb.0:
; NOVSX-NEXT: addis 3, 2, .LCPI4_0@toc@ha
; NOVSX-NEXT: addi 3, 3, .LCPI4_0@toc@l
; NOVSX-NEXT: lvx 3, 0, 3
; NOVSX-NEXT: vsubudm 2, 2, 3
; NOVSX-NEXT: blr
%result = sub <2 x i64> %x, <i64 -1, i64 -1>
ret <2 x i64> %result
}
define <2 x i64> @decrement_by_val(<2 x i64> %x, i64 %val) nounwind {
; VSX-LABEL: decrement_by_val:
; VSX: # %bb.0:
; VSX-NEXT: mtfprd 0, 5
; VSX-NEXT: xxspltd 35, 0, 0
; VSX-NEXT: vsubudm 2, 2, 3
; VSX-NEXT: blr
;
; NOVSX-LABEL: decrement_by_val:
; NOVSX: # %bb.0:
; NOVSX-NEXT: addi 3, 1, -16
; NOVSX-NEXT: std 5, -8(1)
; NOVSX-NEXT: std 5, -16(1)
; NOVSX-NEXT: lvx 3, 0, 3
; NOVSX-NEXT: vsubudm 2, 2, 3
; NOVSX-NEXT: blr
%tmpvec = insertelement <2 x i64> <i64 0, i64 0>, i64 %val, i32 0
%tmpvec2 = insertelement <2 x i64> %tmpvec, i64 %val, i32 1
%result = sub <2 x i64> %x, %tmpvec2
ret <2 x i64> %result
}