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llvm-project/llvm/test/Transforms/LoopVectorize/RISCV/inloop-reduction.ll
Luke Lau 8d16c6809a [RISCV] Increase default vectorizer LMUL to 2 
After some discussion and experimentation, we have seen that changing the default number of vector register bits to LMUL=2 strikes a sweet spot.
Whilst we could be clever here and make the vectorizer smarter about dynamically selecting an LMUL that
a) Doesn't affect register pressure
b) Suitable for the microarchitecture
we would need to teach its heuristics about RISC-V register grouping specifics.
Instead this just does the easy, pragmatic thing by changing the default to a safe value that doesn't affect register pressure signifcantly[1], but should increase throughput and unlock more interleaving.

[1] Register spilling when compiling sqlite at various levels of `-riscv-v-register-bit-width-lmul`:

LMUL=1    2573 spills
LMUL=2    2583 spills
LMUL=4    2819 spills
LMUL=8    3256 spills

Reviewed By: craig.topper

Differential Revision: https://reviews.llvm.org/D143723
2023-03-23 10:33:50 +00:00

137 lines
8.4 KiB
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; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
; RUN: opt -mtriple riscv64-linux-gnu -mattr=+v,+d -passes=loop-vectorize < %s -S -o - | FileCheck %s -check-prefix=OUTLOOP
; RUN: opt -mtriple riscv64-linux-gnu -mattr=+v,+d -passes=loop-vectorize -prefer-inloop-reductions < %s -S -o - | FileCheck %s -check-prefix=INLOOP
target datalayout = "e-m:e-p:64:64-i64:64-i128:128-n64-S128"
target triple = "riscv64"
define i32 @add_i16_i32(ptr nocapture readonly %x, i32 %n) {
; OUTLOOP-LABEL: @add_i16_i32(
; OUTLOOP-NEXT: entry:
; OUTLOOP-NEXT: [[CMP6:%.*]] = icmp sgt i32 [[N:%.*]], 0
; OUTLOOP-NEXT: br i1 [[CMP6]], label [[FOR_BODY_PREHEADER:%.*]], label [[FOR_COND_CLEANUP:%.*]]
; OUTLOOP: for.body.preheader:
; OUTLOOP-NEXT: [[TMP0:%.*]] = call i32 @llvm.vscale.i32()
; OUTLOOP-NEXT: [[TMP1:%.*]] = mul i32 [[TMP0]], 4
; OUTLOOP-NEXT: [[MIN_ITERS_CHECK:%.*]] = icmp ult i32 [[N]], [[TMP1]]
; OUTLOOP-NEXT: br i1 [[MIN_ITERS_CHECK]], label [[SCALAR_PH:%.*]], label [[VECTOR_PH:%.*]]
; OUTLOOP: vector.ph:
; OUTLOOP-NEXT: [[TMP2:%.*]] = call i32 @llvm.vscale.i32()
; OUTLOOP-NEXT: [[TMP3:%.*]] = mul i32 [[TMP2]], 4
; OUTLOOP-NEXT: [[N_MOD_VF:%.*]] = urem i32 [[N]], [[TMP3]]
; OUTLOOP-NEXT: [[N_VEC:%.*]] = sub i32 [[N]], [[N_MOD_VF]]
; OUTLOOP-NEXT: br label [[VECTOR_BODY:%.*]]
; OUTLOOP: vector.body:
; OUTLOOP-NEXT: [[INDEX:%.*]] = phi i32 [ 0, [[VECTOR_PH]] ], [ [[INDEX_NEXT:%.*]], [[VECTOR_BODY]] ]
; OUTLOOP-NEXT: [[VEC_PHI:%.*]] = phi <vscale x 4 x i32> [ zeroinitializer, [[VECTOR_PH]] ], [ [[TMP8:%.*]], [[VECTOR_BODY]] ]
; OUTLOOP-NEXT: [[TMP4:%.*]] = add i32 [[INDEX]], 0
; OUTLOOP-NEXT: [[TMP5:%.*]] = getelementptr inbounds i16, ptr [[X:%.*]], i32 [[TMP4]]
; OUTLOOP-NEXT: [[TMP6:%.*]] = getelementptr inbounds i16, ptr [[TMP5]], i32 0
; OUTLOOP-NEXT: [[WIDE_LOAD:%.*]] = load <vscale x 4 x i16>, ptr [[TMP6]], align 2
; OUTLOOP-NEXT: [[TMP7:%.*]] = sext <vscale x 4 x i16> [[WIDE_LOAD]] to <vscale x 4 x i32>
; OUTLOOP-NEXT: [[TMP8]] = add <vscale x 4 x i32> [[VEC_PHI]], [[TMP7]]
; OUTLOOP-NEXT: [[TMP9:%.*]] = call i32 @llvm.vscale.i32()
; OUTLOOP-NEXT: [[TMP10:%.*]] = mul i32 [[TMP9]], 4
; OUTLOOP-NEXT: [[INDEX_NEXT]] = add nuw i32 [[INDEX]], [[TMP10]]
; OUTLOOP-NEXT: [[TMP11:%.*]] = icmp eq i32 [[INDEX_NEXT]], [[N_VEC]]
; OUTLOOP-NEXT: br i1 [[TMP11]], label [[MIDDLE_BLOCK:%.*]], label [[VECTOR_BODY]], !llvm.loop [[LOOP0:![0-9]+]]
; OUTLOOP: middle.block:
; OUTLOOP-NEXT: [[TMP12:%.*]] = call i32 @llvm.vector.reduce.add.nxv4i32(<vscale x 4 x i32> [[TMP8]])
; OUTLOOP-NEXT: [[CMP_N:%.*]] = icmp eq i32 [[N]], [[N_VEC]]
; OUTLOOP-NEXT: br i1 [[CMP_N]], label [[FOR_COND_CLEANUP_LOOPEXIT:%.*]], label [[SCALAR_PH]]
; OUTLOOP: scalar.ph:
; OUTLOOP-NEXT: [[BC_RESUME_VAL:%.*]] = phi i32 [ [[N_VEC]], [[MIDDLE_BLOCK]] ], [ 0, [[FOR_BODY_PREHEADER]] ]
; OUTLOOP-NEXT: [[BC_MERGE_RDX:%.*]] = phi i32 [ 0, [[FOR_BODY_PREHEADER]] ], [ [[TMP12]], [[MIDDLE_BLOCK]] ]
; OUTLOOP-NEXT: br label [[FOR_BODY:%.*]]
; OUTLOOP: for.body:
; OUTLOOP-NEXT: [[I_08:%.*]] = phi i32 [ [[INC:%.*]], [[FOR_BODY]] ], [ [[BC_RESUME_VAL]], [[SCALAR_PH]] ]
; OUTLOOP-NEXT: [[R_07:%.*]] = phi i32 [ [[ADD:%.*]], [[FOR_BODY]] ], [ [[BC_MERGE_RDX]], [[SCALAR_PH]] ]
; OUTLOOP-NEXT: [[ARRAYIDX:%.*]] = getelementptr inbounds i16, ptr [[X]], i32 [[I_08]]
; OUTLOOP-NEXT: [[TMP13:%.*]] = load i16, ptr [[ARRAYIDX]], align 2
; OUTLOOP-NEXT: [[CONV:%.*]] = sext i16 [[TMP13]] to i32
; OUTLOOP-NEXT: [[ADD]] = add nsw i32 [[R_07]], [[CONV]]
; OUTLOOP-NEXT: [[INC]] = add nuw nsw i32 [[I_08]], 1
; OUTLOOP-NEXT: [[EXITCOND:%.*]] = icmp eq i32 [[INC]], [[N]]
; OUTLOOP-NEXT: br i1 [[EXITCOND]], label [[FOR_COND_CLEANUP_LOOPEXIT]], label [[FOR_BODY]], !llvm.loop [[LOOP3:![0-9]+]]
; OUTLOOP: for.cond.cleanup.loopexit:
; OUTLOOP-NEXT: [[ADD_LCSSA:%.*]] = phi i32 [ [[ADD]], [[FOR_BODY]] ], [ [[TMP12]], [[MIDDLE_BLOCK]] ]
; OUTLOOP-NEXT: br label [[FOR_COND_CLEANUP]]
; OUTLOOP: for.cond.cleanup:
; OUTLOOP-NEXT: [[R_0_LCSSA:%.*]] = phi i32 [ 0, [[ENTRY:%.*]] ], [ [[ADD_LCSSA]], [[FOR_COND_CLEANUP_LOOPEXIT]] ]
; OUTLOOP-NEXT: ret i32 [[R_0_LCSSA]]
;
; INLOOP-LABEL: @add_i16_i32(
; INLOOP-NEXT: entry:
; INLOOP-NEXT: [[CMP6:%.*]] = icmp sgt i32 [[N:%.*]], 0
; INLOOP-NEXT: br i1 [[CMP6]], label [[FOR_BODY_PREHEADER:%.*]], label [[FOR_COND_CLEANUP:%.*]]
; INLOOP: for.body.preheader:
; INLOOP-NEXT: [[TMP0:%.*]] = call i32 @llvm.vscale.i32()
; INLOOP-NEXT: [[TMP1:%.*]] = mul i32 [[TMP0]], 8
; INLOOP-NEXT: [[MIN_ITERS_CHECK:%.*]] = icmp ult i32 [[N]], [[TMP1]]
; INLOOP-NEXT: br i1 [[MIN_ITERS_CHECK]], label [[SCALAR_PH:%.*]], label [[VECTOR_PH:%.*]]
; INLOOP: vector.ph:
; INLOOP-NEXT: [[TMP2:%.*]] = call i32 @llvm.vscale.i32()
; INLOOP-NEXT: [[TMP3:%.*]] = mul i32 [[TMP2]], 8
; INLOOP-NEXT: [[N_MOD_VF:%.*]] = urem i32 [[N]], [[TMP3]]
; INLOOP-NEXT: [[N_VEC:%.*]] = sub i32 [[N]], [[N_MOD_VF]]
; INLOOP-NEXT: br label [[VECTOR_BODY:%.*]]
; INLOOP: vector.body:
; INLOOP-NEXT: [[INDEX:%.*]] = phi i32 [ 0, [[VECTOR_PH]] ], [ [[INDEX_NEXT:%.*]], [[VECTOR_BODY]] ]
; INLOOP-NEXT: [[VEC_PHI:%.*]] = phi i32 [ 0, [[VECTOR_PH]] ], [ [[TMP9:%.*]], [[VECTOR_BODY]] ]
; INLOOP-NEXT: [[TMP4:%.*]] = add i32 [[INDEX]], 0
; INLOOP-NEXT: [[TMP5:%.*]] = getelementptr inbounds i16, ptr [[X:%.*]], i32 [[TMP4]]
; INLOOP-NEXT: [[TMP6:%.*]] = getelementptr inbounds i16, ptr [[TMP5]], i32 0
; INLOOP-NEXT: [[WIDE_LOAD:%.*]] = load <vscale x 8 x i16>, ptr [[TMP6]], align 2
; INLOOP-NEXT: [[TMP7:%.*]] = sext <vscale x 8 x i16> [[WIDE_LOAD]] to <vscale x 8 x i32>
; INLOOP-NEXT: [[TMP8:%.*]] = call i32 @llvm.vector.reduce.add.nxv8i32(<vscale x 8 x i32> [[TMP7]])
; INLOOP-NEXT: [[TMP9]] = add i32 [[TMP8]], [[VEC_PHI]]
; INLOOP-NEXT: [[TMP10:%.*]] = call i32 @llvm.vscale.i32()
; INLOOP-NEXT: [[TMP11:%.*]] = mul i32 [[TMP10]], 8
; INLOOP-NEXT: [[INDEX_NEXT]] = add nuw i32 [[INDEX]], [[TMP11]]
; INLOOP-NEXT: [[TMP12:%.*]] = icmp eq i32 [[INDEX_NEXT]], [[N_VEC]]
; INLOOP-NEXT: br i1 [[TMP12]], label [[MIDDLE_BLOCK:%.*]], label [[VECTOR_BODY]], !llvm.loop [[LOOP0:![0-9]+]]
; INLOOP: middle.block:
; INLOOP-NEXT: [[CMP_N:%.*]] = icmp eq i32 [[N]], [[N_VEC]]
; INLOOP-NEXT: br i1 [[CMP_N]], label [[FOR_COND_CLEANUP_LOOPEXIT:%.*]], label [[SCALAR_PH]]
; INLOOP: scalar.ph:
; INLOOP-NEXT: [[BC_RESUME_VAL:%.*]] = phi i32 [ [[N_VEC]], [[MIDDLE_BLOCK]] ], [ 0, [[FOR_BODY_PREHEADER]] ]
; INLOOP-NEXT: [[BC_MERGE_RDX:%.*]] = phi i32 [ 0, [[FOR_BODY_PREHEADER]] ], [ [[TMP9]], [[MIDDLE_BLOCK]] ]
; INLOOP-NEXT: br label [[FOR_BODY:%.*]]
; INLOOP: for.body:
; INLOOP-NEXT: [[I_08:%.*]] = phi i32 [ [[INC:%.*]], [[FOR_BODY]] ], [ [[BC_RESUME_VAL]], [[SCALAR_PH]] ]
; INLOOP-NEXT: [[R_07:%.*]] = phi i32 [ [[ADD:%.*]], [[FOR_BODY]] ], [ [[BC_MERGE_RDX]], [[SCALAR_PH]] ]
; INLOOP-NEXT: [[ARRAYIDX:%.*]] = getelementptr inbounds i16, ptr [[X]], i32 [[I_08]]
; INLOOP-NEXT: [[TMP13:%.*]] = load i16, ptr [[ARRAYIDX]], align 2
; INLOOP-NEXT: [[CONV:%.*]] = sext i16 [[TMP13]] to i32
; INLOOP-NEXT: [[ADD]] = add nsw i32 [[R_07]], [[CONV]]
; INLOOP-NEXT: [[INC]] = add nuw nsw i32 [[I_08]], 1
; INLOOP-NEXT: [[EXITCOND:%.*]] = icmp eq i32 [[INC]], [[N]]
; INLOOP-NEXT: br i1 [[EXITCOND]], label [[FOR_COND_CLEANUP_LOOPEXIT]], label [[FOR_BODY]], !llvm.loop [[LOOP3:![0-9]+]]
; INLOOP: for.cond.cleanup.loopexit:
; INLOOP-NEXT: [[ADD_LCSSA:%.*]] = phi i32 [ [[ADD]], [[FOR_BODY]] ], [ [[TMP9]], [[MIDDLE_BLOCK]] ]
; INLOOP-NEXT: br label [[FOR_COND_CLEANUP]]
; INLOOP: for.cond.cleanup:
; INLOOP-NEXT: [[R_0_LCSSA:%.*]] = phi i32 [ 0, [[ENTRY:%.*]] ], [ [[ADD_LCSSA]], [[FOR_COND_CLEANUP_LOOPEXIT]] ]
; INLOOP-NEXT: ret i32 [[R_0_LCSSA]]
;
entry:
%cmp6 = icmp sgt i32 %n, 0
br i1 %cmp6, label %for.body, label %for.cond.cleanup
for.body: ; preds = %entry, %for.body
%i.08 = phi i32 [ %inc, %for.body ], [ 0, %entry ]
%r.07 = phi i32 [ %add, %for.body ], [ 0, %entry ]
%arrayidx = getelementptr inbounds i16, ptr %x, i32 %i.08
%0 = load i16, ptr %arrayidx, align 2
%conv = sext i16 %0 to i32
%add = add nsw i32 %r.07, %conv
%inc = add nuw nsw i32 %i.08, 1
%exitcond = icmp eq i32 %inc, %n
br i1 %exitcond, label %for.cond.cleanup, label %for.body
for.cond.cleanup: ; preds = %for.body, %entry
%r.0.lcssa = phi i32 [ 0, %entry ], [ %add, %for.body ]
ret i32 %r.0.lcssa
}
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