| ; RUN: opt < %s -S -unroll-runtime -unroll-count=2 -loop-unroll | FileCheck %s |
| target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128" |
| |
| ; When prologue is fully unrolled, the branch on its end is unconditional. |
| ; Unrolling it is illegal if we can't prove that trip-count+1 doesn't overflow, |
| ; like in this example, where it comes from an argument. |
| ; |
| ; This test is based on an example from here: |
| ; http://stackoverflow.com/questions/23838661/why-is-clang-optimizing-this-code-out |
| ; |
| ; CHECK: while.body.prol: |
| ; CHECK: br i1 |
| ; CHECK: entry.split: |
| |
| ; Function Attrs: nounwind readnone ssp uwtable |
| define i32 @foo(i32 %N) #0 { |
| entry: |
| br label %while.body |
| |
| while.body: ; preds = %while.body, %entry |
| %i = phi i32 [ 0, %entry ], [ %inc, %while.body ] |
| %cmp = icmp eq i32 %i, %N |
| %inc = add i32 %i, 1 |
| br i1 %cmp, label %while.end, label %while.body |
| |
| while.end: ; preds = %while.body |
| ret i32 %i |
| } |
| |
| attributes #0 = { nounwind readnone ssp uwtable "less-precise-fpmad"="false" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "stack-protector-buffer-size"="8" "unsafe-fp-math"="false" "use-soft-float"="false" } |