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llvm-mirror/test/Analysis/ScalarEvolution/max-trip-count.ll
Dan Gohman 603e66618f When analyzing loop exit conditions combined with and and or, don't
make any assumptions about when the two conditions will agree on when
to permit the loop to exit. This fixes PR7845.

llvm-svn: 110758
2010-08-11 00:12:36 +00:00

73 lines
2.5 KiB
LLVM

; RUN: opt < %s -analyze -scalar-evolution | FileCheck %s
; ScalarEvolution should be able to understand the loop and eliminate the casts.
; CHECK: {%d,+,sizeof(i32)}
define void @foo(i32* nocapture %d, i32 %n) nounwind {
entry:
%0 = icmp sgt i32 %n, 0 ; <i1> [#uses=1]
br i1 %0, label %bb.nph, label %return
bb.nph: ; preds = %entry
br label %bb
bb: ; preds = %bb1, %bb.nph
%i.02 = phi i32 [ %5, %bb1 ], [ 0, %bb.nph ] ; <i32> [#uses=2]
%p.01 = phi i8 [ %4, %bb1 ], [ -1, %bb.nph ] ; <i8> [#uses=2]
%1 = sext i8 %p.01 to i32 ; <i32> [#uses=1]
%2 = sext i32 %i.02 to i64 ; <i64> [#uses=1]
%3 = getelementptr i32* %d, i64 %2 ; <i32*> [#uses=1]
store i32 %1, i32* %3, align 4
%4 = add i8 %p.01, 1 ; <i8> [#uses=1]
%5 = add i32 %i.02, 1 ; <i32> [#uses=2]
br label %bb1
bb1: ; preds = %bb
%6 = icmp slt i32 %5, %n ; <i1> [#uses=1]
br i1 %6, label %bb, label %bb1.return_crit_edge
bb1.return_crit_edge: ; preds = %bb1
br label %return
return: ; preds = %bb1.return_crit_edge, %entry
ret void
}
; ScalarEvolution should be able to find the maximum tripcount
; of this multiple-exit loop, and if it doesn't know the exact
; count, it should say so.
; PR7845
; CHECK: Loop %for.cond: <multiple exits> Unpredictable backedge-taken count.
; CHECK: Loop %for.cond: max backedge-taken count is 5
@.str = private constant [4 x i8] c"%d\0A\00" ; <[4 x i8]*> [#uses=2]
define i32 @main() nounwind {
entry:
br label %for.cond
for.cond: ; preds = %for.inc, %entry
%g_4.0 = phi i32 [ 0, %entry ], [ %add, %for.inc ] ; <i32> [#uses=5]
%cmp = icmp slt i32 %g_4.0, 5 ; <i1> [#uses=1]
br i1 %cmp, label %for.body, label %for.end
for.body: ; preds = %for.cond
%conv = trunc i32 %g_4.0 to i16 ; <i16> [#uses=1]
%tobool.not = icmp eq i16 %conv, 0 ; <i1> [#uses=1]
%tobool3 = icmp ne i32 %g_4.0, 0 ; <i1> [#uses=1]
%or.cond = and i1 %tobool.not, %tobool3 ; <i1> [#uses=1]
br i1 %or.cond, label %for.end, label %for.inc
for.inc: ; preds = %for.body
%add = add nsw i32 %g_4.0, 1 ; <i32> [#uses=1]
br label %for.cond
for.end: ; preds = %for.body, %for.cond
%call = call i32 (i8*, ...)* @printf(i8* getelementptr inbounds ([4 x i8]* @.str, i64 0, i64 0), i32 %g_4.0) nounwind ; <i32> [#uses=0]
ret i32 0
}
declare i32 @printf(i8*, ...)