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https://github.com/c64scene-ar/llvm-6502.git
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62baa594d7
HowFarToZero was supposed to use unsigned division in order to calculate the backedge taken count. However, SCEVDivision::divide performs signed division. Unless I am mistaken, no users of SCEVDivision actually want signed arithmetic: switch to udiv and urem. This fixes PR21578. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@222093 91177308-0d34-0410-b5e6-96231b3b80d8
54 lines
1.3 KiB
LLVM
54 lines
1.3 KiB
LLVM
; RUN: opt < %s -scalar-evolution -analyze | FileCheck %s
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define void @test1(i32 %n) {
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entry:
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%s = mul i32 %n, 96
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br label %loop
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loop:
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%i = phi i32 [ 0, %entry ], [ %i.next, %loop ]
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%i.next = add i32 %i, 32
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%t = icmp ne i32 %i.next, %s
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br i1 %t, label %loop, label %exit
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exit:
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ret void
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; CHECK-LABEL: @test1
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; CHECK: Loop %loop: backedge-taken count is ((-32 + (96 * %n)) /u 32)
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; CHECK: Loop %loop: max backedge-taken count is ((-32 + (96 * %n)) /u 32)
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}
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; PR19183
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define i32 @test2(i32 %n) {
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entry:
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%s = and i32 %n, -32
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br label %loop
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loop:
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%i = phi i32 [ 0, %entry ], [ %i.next, %loop ]
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%i.next = add i32 %i, 32
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%t = icmp ne i32 %i.next, %s
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br i1 %t, label %loop, label %exit
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exit:
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ret i32 %i
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; CHECK-LABEL: @test2
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; CHECK: Loop %loop: backedge-taken count is ((-32 + (32 * (%n /u 32))) /u 32)
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; CHECK: Loop %loop: max backedge-taken count is ((-32 + (32 * (%n /u 32))) /u 32)
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}
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define void @test3(i32 %n) {
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entry:
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%s = mul i32 %n, 96
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br label %loop
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loop:
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%i = phi i32 [ 0, %entry ], [ %i.next, %loop ]
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%i.next = add i32 %i, 96
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%t = icmp ne i32 %i.next, %s
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br i1 %t, label %loop, label %exit
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exit:
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ret void
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; CHECK-LABEL: @test3
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; CHECK: Loop %loop: Unpredictable backedge-taken count.
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; CHECK: Loop %loop: Unpredictable max backedge-taken count.
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}
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