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https://github.com/c64scene-ar/llvm-6502.git
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a0a0b40aa3
(The change was landed in r230280 and caused the regression PR22674.
This version contains a fix and a test-case for PR22674).
When emitting the increment operation, SCEVExpander marks the
operation as nuw or nsw based on the flags on the preincrement SCEV.
This is incorrect because, for instance, it is possible that {-6,+,1}
is <nuw> while {-6,+,1}+1 = {-5,+,1} is not.
This change teaches SCEV to mark the increment as nuw/nsw only if it
can explicitly prove that the increment operation won't overflow.
Apart from the attached test case, another (more realistic)
manifestation of the bug can be seen in
Transforms/IndVarSimplify/pr20680.ll.
Differential Revision: http://reviews.llvm.org/D7778
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@230533 91177308-0d34-0410-b5e6-96231b3b80d8
57 lines
1.6 KiB
LLVM
57 lines
1.6 KiB
LLVM
; RUN: opt < %s -indvars -liv-reduce -S | FileCheck %s
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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"
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target triple = "x86_64-apple-macosx"
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; CHECK-LABEL: @addwithoverflow
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; CHECK-LABEL: loop1:
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; CHECK-NOT: zext
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; CHECK: add nsw
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; CHECK: @llvm.sadd.with.overflow
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; CHECK-LABEL: loop2:
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; CHECK-NOT: extractvalue
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; CHECK: add nuw
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; CHECK: @llvm.sadd.with.overflow
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; CHECK-LABEL: loop3:
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; CHECK-NOT: extractvalue
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; CHECK: ret
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define i64 @addwithoverflow(i32 %n, i64* %a) {
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entry:
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br label %loop0
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loop0:
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%i = phi i32 [ 0, %entry ], [ %i1val, %loop3 ]
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%s = phi i32 [ 0, %entry ], [ %addsval, %loop3 ]
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%bc = icmp ult i32 %i, %n
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br i1 %bc, label %loop1, label %exit
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loop1:
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%zxt = zext i32 %i to i64
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%ofs = shl nuw nsw i64 %zxt, 3
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%gep = getelementptr i64* %a, i64 %zxt
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%v = load i64* %gep, align 8
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%truncv = trunc i64 %v to i32
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%adds = call { i32, i1 } @llvm.sadd.with.overflow.i32(i32 %s, i32 %truncv)
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%ovflows = extractvalue { i32, i1 } %adds, 1
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br i1 %ovflows, label %exit, label %loop2
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loop2:
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%addsval = extractvalue { i32, i1 } %adds, 0
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%i1 = call { i32, i1 } @llvm.sadd.with.overflow.i32(i32 %i, i32 1)
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%i1check = extractvalue { i32, i1 } %i1, 1
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br i1 %i1check, label %exit, label %loop3
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loop3:
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%i1val = extractvalue { i32, i1 } %i1, 0
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%test = icmp slt i32 %i1val, %n
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br i1 %test, label %return, label %loop0
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return:
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%ret = zext i32 %addsval to i64
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ret i64 %ret
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exit:
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unreachable
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}
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declare { i32, i1 } @llvm.sadd.with.overflow.i32(i32, i32)
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