llvm/test/Transforms/IndVarSimplify/2011-11-15-multiexit.ll
Andrew Trick 79f0bfcc20 Fix SCEV overly optimistic back edge taken count for multi-exit loops.
Fixes PR11375: Different results for 'clang++ huh.cpp'...


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@144746 91177308-0d34-0410-b5e6-96231b3b80d8
2011-11-16 00:52:40 +00:00

41 lines
1.6 KiB
LLVM

; RUN: opt < %s -indvars -S | FileCheck %s
;
; Prior to the fix for PR11375, indvars would replace %firstIV with a
; loop-invariant gep computed in the preheader. This was incorrect
; because it was based on the minimum "ExitNotTaken" count. If the
; final loop test is skipped (odd number of elements) then the early
; exit would be taken and the loop invariant value would be incorrect.
target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
target triple = "x86_64-apple-darwin"
; CHECK: if.end:
; CHECK: phi i32* [ %first.lcssa, %early.exit ]
define i32 @test(i32* %first, i32* %last) uwtable ssp {
entry:
br i1 undef, label %if.end, label %if.then
if.then: ; preds = %entry
br i1 undef, label %if.end, label %do.body
do.body: ; preds = %if.else, %if.then
%firstIV = phi i32* [ %incdec.ptr2, %if.else ], [ %first, %if.then ]
%incdec.ptr1 = getelementptr inbounds i32* %firstIV, i64 1
%cmp1 = icmp eq i32* %incdec.ptr1, %last
br i1 %cmp1, label %early.exit, label %if.else
if.else: ; preds = %do.body
%incdec.ptr2 = getelementptr inbounds i32* %firstIV, i64 2
%cmp2 = icmp eq i32* %incdec.ptr2, %last
br i1 %cmp2, label %if.end, label %do.body
early.exit:
%first.lcssa = phi i32* [ %firstIV, %do.body ]
br label %if.end
if.end:
%tmp = phi i32* [ %first.lcssa, %early.exit ], [ %first, %if.then ], [ %first, %entry ], [ undef, %if.else ]
%val = load i32* %tmp
ret i32 %val
}