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llvm-mirror/test/Transforms/LICM/preheader-safe.ll
Xin Tong 3093d25a9a Compute safety information in a much finer granularity.
Summary:
Instead of keeping a variable indicating whether there are early exits
in the loop.  We keep all the early exits. This improves LICM's ability to
move instructions out of the loop based on is-guaranteed-to-execute.

I am going to update compilation time as well soon.

Reviewers: hfinkel, sanjoy, efriedma, mkuper

Reviewed By: hfinkel

Subscribers: llvm-commits, mzolotukhin

Differential Revision: https://reviews.llvm.org/D32433

llvm-svn: 301196
2017-04-24 17:12:22 +00:00

60 lines
1.6 KiB
LLVM

; RUN: opt -S -licm < %s | FileCheck %s
; RUN: opt -aa-pipeline=basic-aa -passes='require<aa>,require<targetir>,require<scalar-evolution>,require<opt-remark-emit>,loop(licm)' -S %s | FileCheck %s
declare void @use_nothrow(i64 %a) nounwind
declare void @use(i64 %a)
define void @nothrow(i64 %x, i64 %y, i1* %cond) {
; CHECK-LABEL: nothrow
; CHECK-LABEL: entry
; CHECK: %div = udiv i64 %x, %y
; CHECK-LABEL: loop
; CHECK: call void @use_nothrow(i64 %div)
entry:
br label %loop
loop: ; preds = %entry, %for.inc
%div = udiv i64 %x, %y
br label %loop2
loop2:
call void @use_nothrow(i64 %div)
br label %loop
}
; The header is known no throw, but the loop is not. We can
; still lift out of the header.
define void @nothrow_header(i64 %x, i64 %y, i1 %cond) {
; CHECK-LABEL: nothrow_header
; CHECK-LABEL: entry
; CHECK: %div = udiv i64 %x, %y
; CHECK-LABEL: loop
; CHECK: call void @use(i64 %div)
entry:
br label %loop
loop: ; preds = %entry, %for.inc
%div = udiv i64 %x, %y
br i1 %cond, label %loop-if, label %exit
loop-if:
call void @use(i64 %div)
br label %loop
exit:
ret void
}
; Negative test - can't move out of throwing block
define void @nothrow_header_neg(i64 %x, i64 %y, i1 %cond) {
; CHECK-LABEL: nothrow_header_neg
; CHECK-LABEL: entry
; CHECK-LABEL: loop
; CHECK: %div = udiv i64 %x, %y
; CHECK: call void @use(i64 %div)
entry:
br label %loop
loop: ; preds = %entry, %for.inc
br label %loop-if
loop-if:
%div = udiv i64 %x, %y
call void @use(i64 %div)
br label %loop
}