File: 2002-05-02-EdgeFailure.ll

package info (click to toggle)
llvm 2.6-9.1
  • links: PTS
  • area: main
  • in suites: squeeze
  • size: 57,604 kB
  • ctags: 44,336
  • sloc: cpp: 344,766; sh: 12,407; ansic: 10,617; ada: 3,070; ml: 2,505; perl: 2,496; makefile: 1,426; pascal: 1,163; exp: 389; asm: 307; python: 298; objc: 260; lisp: 182; csh: 117; xml: 38; f90: 36; tcl: 20
file content (26 lines) | stat: -rw-r--r-- 933 bytes parent folder | download
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
; edgefailure - This function illustrates how SCCP is not doing it's job.  This
; function should be optimized almost completely away: the loop should be
; analyzed to detect that the body executes exactly once, and thus the branch
; can be eliminated and code becomes trivially dead.  This is distilled from a
; real benchmark (mst from Olden benchmark, MakeGraph function).  When SCCP is
; fixed, this should be eliminated by a single SCCP application.
;
; RUN: llvm-as < %s | opt -sccp | llvm-dis | not grep loop

define i32* @test() {
bb1:
	%A = malloc i32		; <i32*> [#uses=2]
	br label %bb2
bb2:		; preds = %bb2, %bb1
        ;; Always 0
	%i = phi i32 [ %i2, %bb2 ], [ 0, %bb1 ]		; <i32> [#uses=2]
        ;; Always 1
	%i2 = add i32 %i, 1		; <i32> [#uses=2]
	store i32 %i, i32* %A
        ;; Always false
  	%loop = icmp sle i32 %i2, 0		; <i1> [#uses=1]
	br i1 %loop, label %bb2, label %bb3
bb3:		; preds = %bb2
	ret i32* %A
}