llvm-6502/test/Transforms/LoopUnroll/runtime-loop1.ll
Michael Zolotukhin 4e7b10b07f Fix a trip-count overflow issue in LoopUnroll.
Currently LoopUnroll generates a prologue loop before the main loop
body to execute first N%UnrollFactor iterations. Also, this loop is
used if trip-count can overflow - it's determined by a runtime check.

However, we've been mistakenly optimizing this loop to a linear code for
UnrollFactor = 2, not taking into account that it also serves as a safe
version of the loop if its trip-count overflows.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@222451 91177308-0d34-0410-b5e6-96231b3b80d8
2014-11-20 20:19:55 +00:00

31 lines
1.2 KiB
LLVM

; RUN: opt < %s -S -loop-unroll -unroll-runtime -unroll-count=2 | FileCheck %s
; This tests that setting the unroll count works
; CHECK: for.body.prol:
; CHECK: br i1 %prol.iter.cmp, label %for.body.prol, label %for.body.preheader.split
; CHECK: for.body:
; CHECK: br i1 %exitcond.1, label %for.end.loopexit.unr-lcssa, label %for.body
; CHECK-NOT: br i1 %exitcond.4, label %for.end.loopexit{{.*}}, label %for.body
define i32 @test(i32* nocapture %a, i32 %n) nounwind uwtable readonly {
entry:
%cmp1 = icmp eq i32 %n, 0
br i1 %cmp1, label %for.end, label %for.body
for.body: ; preds = %for.body, %entry
%indvars.iv = phi i64 [ %indvars.iv.next, %for.body ], [ 0, %entry ]
%sum.02 = phi i32 [ %add, %for.body ], [ 0, %entry ]
%arrayidx = getelementptr inbounds i32* %a, i64 %indvars.iv
%0 = load i32* %arrayidx, align 4
%add = add nsw i32 %0, %sum.02
%indvars.iv.next = add i64 %indvars.iv, 1
%lftr.wideiv = trunc i64 %indvars.iv.next to i32
%exitcond = icmp eq i32 %lftr.wideiv, %n
br i1 %exitcond, label %for.end, label %for.body
for.end: ; preds = %for.body, %entry
%sum.0.lcssa = phi i32 [ 0, %entry ], [ %add, %for.body ]
ret i32 %sum.0.lcssa
}