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llvm-mirror/test/Transforms/JumpThreading/no-irreducible-loops.ll
Chris Lattner 6807ddd3d9 * Sink 4 duplicates of edge threading validity checks and DOUT prints into
ThreadEdge directly.  This shares the code, but is just a refactoring.
* Make JumpThreading compute the set of loop headers and avoid threading
  across them.  This prevents jump threading from forming irreducible 
  loops (goodness) but also prevents it from threading in other cases that
  are beneficial (see the comment above FindFunctionBackedges).

llvm-svn: 70820
2009-05-04 02:28:08 +00:00

39 lines
1.1 KiB
LLVM

; RUN: llvm-as < %s | opt -jump-threading -loop-rotate -instcombine -indvars -loop-unroll -simplifycfg | llvm-dis > %t
; RUN: grep {volatile store} %t | count 3
; RUN: not grep {br label} %t
; Jump threading should not prevent this loop from being unrolled.
target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:128:128"
target triple = "i386-apple-darwin9.6"
@v1 = external global i32 ; <i32*> [#uses=2]
define i32 @unroll() nounwind {
entry:
br label %bb4
bb: ; preds = %bb4
%0 = icmp eq i32 %i.0, 0 ; <i1> [#uses=1]
br i1 %0, label %bb1, label %bb2
bb1: ; preds = %bb
volatile store i32 1000, i32* @v1, align 4
br label %bb3
bb2: ; preds = %bb
volatile store i32 1001, i32* @v1, align 4
br label %bb3
bb3: ; preds = %bb2, %bb1
%1 = add i32 %i.0, 1 ; <i32> [#uses=1]
br label %bb4
bb4: ; preds = %bb3, %entry
%i.0 = phi i32 [ 0, %entry ], [ %1, %bb3 ] ; <i32> [#uses=3]
%2 = icmp sgt i32 %i.0, 2 ; <i1> [#uses=1]
br i1 %2, label %bb5, label %bb
bb5: ; preds = %bb4
ret i32 0
}