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Reimplement heuristic for estimating complete-unroll optimization effects.

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Summary:
This patch reimplements heuristic that tries to estimate optimization beneftis
from complete loop unrolling.

In this patch I kept the minimal changes - e.g. I removed code handling
branches and folding compares. That's a promising area, but now there
are too many questions to discuss before we can enable it.

Test Plan: Tests are included in the patch.

Reviewers: hfinkel, chandlerc

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D8816

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@237156 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Michael Zolotukhin
2015-05-12 17:20:03 +00:00
parent 2c3514ae0d
commit e2d9012a38
3 changed files with 333 additions and 247 deletions
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34
test/Transforms/LoopUnroll/full-unroll-bad-geps.ll Normal file
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@@ -0,0 +1,34 @@
; Check that we don't crash on corner cases.
; RUN: opt < %s -S -loop-unroll -unroll-max-iteration-count-to-analyze=1000 -unroll-absolute-threshold=10 -unroll-threshold=10 -unroll-percent-of-optimized-for-complete-unroll=20 -o /dev/null
target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
define void @foo1() {
entry:
br label %for.body
for.body:
%phi = phi i64 [ 0, %entry ], [ %inc, %for.body ]
%idx = zext i32 undef to i64
%add.ptr = getelementptr inbounds i64, i64* null, i64 %idx
%inc = add nuw nsw i64 %phi, 1
%cmp = icmp ult i64 %inc, 999
br i1 %cmp, label %for.body, label %for.exit
for.exit:
ret void
}
define void @foo2() {
entry:
br label %for.body
for.body:
%phi = phi i64 [ 0, %entry ], [ %inc, %for.body ]
%x = getelementptr i32, <4 x i32*> undef, <4 x i32> <i32 1, i32 1, i32 1, i32 1>
%inc = add nuw nsw i64 %phi, 1
%cmp = icmp ult i64 %inc, 999
br i1 %cmp, label %for.body, label %for.exit
for.exit:
ret void
}

4
test/Transforms/LoopUnroll/full-unroll-heuristics.ll
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@@ -17,8 +17,8 @@
; optimizations to remove ~55% of the instructions, the loop body size is 9,
; and unrolled size is 65.
; RUN: opt < %s -S -loop-unroll -unroll-max-iteration-count-to-analyze=1000 -unroll-absolute-threshold=10 -unroll-threshold=10 -unroll-percent-of-optimized-for-complete-unroll=30 | FileCheck %s -check-prefix=TEST1
; RUN: opt < %s -S -loop-unroll -unroll-max-iteration-count-to-analyze=1000 -unroll-absolute-threshold=100 -unroll-threshold=10 -unroll-percent-of-optimized-for-complete-unroll=30 | FileCheck %s -check-prefix=TEST2
; RUN: opt < %s -S -loop-unroll -unroll-max-iteration-count-to-analyze=1000 -unroll-absolute-threshold=10 -unroll-threshold=10 -unroll-percent-of-optimized-for-complete-unroll=20 | FileCheck %s -check-prefix=TEST1
; RUN: opt < %s -S -loop-unroll -unroll-max-iteration-count-to-analyze=1000 -unroll-absolute-threshold=100 -unroll-threshold=10 -unroll-percent-of-optimized-for-complete-unroll=20 | FileCheck %s -check-prefix=TEST2
; RUN: opt < %s -S -loop-unroll -unroll-max-iteration-count-to-analyze=1000 -unroll-absolute-threshold=100 -unroll-threshold=10 -unroll-percent-of-optimized-for-complete-unroll=80 | FileCheck %s -check-prefix=TEST3
; RUN: opt < %s -S -loop-unroll -unroll-max-iteration-count-to-analyze=1000 -unroll-absolute-threshold=100 -unroll-threshold=100 -unroll-percent-of-optimized-for-complete-unroll=80 | FileCheck %s -check-prefix=TEST4