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[AArch64] Enable Upper bound unrolling universally 

Differential Revision: https://reviews.llvm.org/D105996
This commit is contained in:
Jingu Kang 2021-07-14 11:43:29 +01:00
parent 5b06cbac11
commit 94c4952951
2 changed files with 67 additions and 1 deletions
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3
llvm/lib/Target/AArch64/AArch64TargetTransformInfo.cpp
View File

@ -1754,6 +1754,8 @@ void AArch64TTIImpl::getUnrollingPreferences(Loop *L, ScalarEvolution &SE,
// Enable partial unrolling and runtime unrolling.
BaseT::getUnrollingPreferences(L, SE, UP, ORE);
UP.UpperBound = true;
// For inner loop, it is more likely to be a hot one, and the runtime check
// can be promoted out from LICM pass, so the overhead is less, let's try
// a larger threshold to unroll more loops.
@ -1794,7 +1796,6 @@ void AArch64TTIImpl::getUnrollingPreferences(Loop *L, ScalarEvolution &SE,
!ST->getSchedModel().isOutOfOrder()) {
UP.Runtime = true;
UP.Partial = true;
UP.UpperBound = true;
UP.UnrollRemainder = true;
UP.DefaultUnrollRuntimeCount = 4;

65
llvm/test/Transforms/LoopUnroll/AArch64/unroll-upperbound.ll Normal file
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@ -0,0 +1,65 @@
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
; RUN: opt < %s -S -loop-unroll -mtriple aarch64 | FileCheck %s
; Below loop's trip count is not constant and it blocks to unroll the loop.
; After setting up `UP.UpperBound = true` in `getUnrollingPreferences`,
; the loop should be unrolled.
define void @test(i1 %cond) {
; CHECK-LABEL: @test(
; CHECK-NEXT: entry:
; CHECK-NEXT: br label [[FOR_BODY:%.*]]
; CHECK: for.body:
; CHECK-NEXT: switch i32 0, label [[SW_DEFAULT:%.*]] [
; CHECK-NEXT: i32 2, label [[LATCH:%.*]]
; CHECK-NEXT: ]
; CHECK: sw.default:
; CHECK-NEXT: tail call void @foo()
; CHECK-NEXT: br label [[LATCH]]
; CHECK: latch:
; CHECK-NEXT: br i1 false, label [[FOR_END:%.*]], label [[FOR_BODY_1:%.*]]
; CHECK: for.end:
; CHECK-NEXT: ret void
; CHECK: for.body.1:
; CHECK-NEXT: switch i32 1, label [[SW_DEFAULT_1:%.*]] [
; CHECK-NEXT: i32 2, label [[LATCH_1:%.*]]
; CHECK-NEXT: ]
; CHECK: sw.default.1:
; CHECK-NEXT: tail call void @foo()
; CHECK-NEXT: br label [[LATCH_1]]
; CHECK: latch.1:
; CHECK-NEXT: br i1 [[COND:%.*]], label [[FOR_END]], label [[FOR_BODY_2:%.*]]
; CHECK: for.body.2:
; CHECK-NEXT: switch i32 2, label [[SW_DEFAULT_2:%.*]] [
; CHECK-NEXT: i32 2, label [[LATCH_2:%.*]]
; CHECK-NEXT: ]
; CHECK: sw.default.2:
; CHECK-NEXT: tail call void @foo()
; CHECK-NEXT: br label [[LATCH_2]]
; CHECK: latch.2:
; CHECK-NEXT: br label [[FOR_END]]
;
entry:
%0 = select i1 %cond, i32 2, i32 3
br label %for.body
for.body:
%i.017 = phi i32 [ 0, %entry ], [ %inc, %latch ]
switch i32 %i.017, label %sw.default [
i32 2, label %latch
]
sw.default:
tail call void @foo()
br label %latch
latch:
%inc = add nuw nsw i32 %i.017, 1
%exitcond.not = icmp eq i32 %inc, %0
br i1 %exitcond.not, label %for.end, label %for.body
for.end:
ret void
}
declare void @foo()