trip-count-unknown-stride.ll
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; RUN: opt < %s -analyze -enable-new-pm=0 -scalar-evolution | FileCheck %s
; RUN: opt < %s -disable-output "-passes=print<scalar-evolution>" 2>&1 | FileCheck %s
; ScalarEvolution should be able to compute trip count of the loop by proving
; that this is not an infinite loop with side effects.
; CHECK: Determining loop execution counts for: @foo1
; CHECK: backedge-taken count is ((-1 + %n) /u %s)
; We should have a conservative estimate for the max backedge taken count for
; loops with unknown stride.
; CHECK: max backedge-taken count is -1
target datalayout = "e-m:e-p:32:32-f64:32:64-f80:32-n8:16:32-S128"
; Function Attrs: norecurse nounwind
define void @foo1(i32* nocapture %A, i32 %n, i32 %s) #0 {
entry:
%cmp4 = icmp sgt i32 %n, 0
br i1 %cmp4, label %for.body, label %for.end
for.body: ; preds = %entry, %for.body
%i.05 = phi i32 [ %add, %for.body ], [ 0, %entry ]
%arrayidx = getelementptr inbounds i32, i32* %A, i32 %i.05
%0 = load i32, i32* %arrayidx, align 4
%inc = add nsw i32 %0, 1
store i32 %inc, i32* %arrayidx, align 4
%add = add nsw i32 %i.05, %s
%cmp = icmp slt i32 %add, %n
br i1 %cmp, label %for.body, label %for.end
for.end: ; preds = %for.body, %entry
ret void
}
; Check that we are able to compute trip count of a loop without an entry guard.
; CHECK: Determining loop execution counts for: @foo2
; CHECK: backedge-taken count is ((-1 + (%n smax %s)) /u %s)
; We should have a conservative estimate for the max backedge taken count for
; loops with unknown stride.
; CHECK: max backedge-taken count is -1
; Function Attrs: norecurse nounwind
define void @foo2(i32* nocapture %A, i32 %n, i32 %s) #0 {
entry:
br label %for.body
for.body: ; preds = %entry, %for.body
%i.05 = phi i32 [ %add, %for.body ], [ 0, %entry ]
%arrayidx = getelementptr inbounds i32, i32* %A, i32 %i.05
%0 = load i32, i32* %arrayidx, align 4
%inc = add nsw i32 %0, 1
store i32 %inc, i32* %arrayidx, align 4
%add = add nsw i32 %i.05, %s
%cmp = icmp slt i32 %add, %n
br i1 %cmp, label %for.body, label %for.end
for.end: ; preds = %for.body, %entry
ret void
}