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1fa642776c
To avoid regressions, make ScalarEvolution::createSCEV a bit more clever. Also get rid of some useless code in ScalarEvolution::howFarToZero which was hiding this bug. No new testcase because it's impossible to actually expose this bug: we don't have any in-tree users of getUDivExactExpr besides the two functions I just mentioned, and they both dodged the problem. I'll try to add some interesting users in a followup. Differential Revision: https://reviews.llvm.org/D28587 llvm-svn: 292449
36 lines
962 B
LLVM
36 lines
962 B
LLVM
; RUN: opt -analyze -scalar-evolution < %s | FileCheck %s
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; CHECK: Loop %bb1: backedge-taken count is ((2 * %a.promoted) /u 2)
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target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
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target triple = "x86_64-apple-macosx10.10.0"
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@a = global i8 -127, align 1
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@b = common global i32 0, align 4
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declare void @use(i32)
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define i32 @main() {
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bb:
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%a.promoted = load i8, i8* @a
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br label %bb1
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bb1: ; preds = %bb1, %bb
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%tmp = phi i8 [ %tmp2, %bb1 ], [ %a.promoted, %bb ]
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%tmp2 = add i8 %tmp, -1
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%tmp3 = sext i8 %tmp to i32
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%tmp4 = xor i32 %tmp3, -1
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%tmp5 = sext i8 %tmp2 to i32
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%tmpf = sub nsw i32 %tmp4, %tmp5
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%tmp6 = trunc i32 %tmpf to i8
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%tmp7 = icmp eq i8 %tmp6, 0
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br i1 %tmp7, label %bb8, label %bb1
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bb8: ; preds = %bb1
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store i8 %tmp2, i8* @a
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store i32 %tmp4, i32* @b
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%tmp9 = sext i8 %tmp2 to i32
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call void @use(i32 %tmp9)
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ret i32 0
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}
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