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[SCEV] Make SCEV or modeling more aggressive.
Use haveNoCommonBitsSet to figure out whether an "or" instruction is equivalent to addition. This handles more cases than just checking for a constant on the RHS. Differential Revision: https://reviews.llvm.org/D32239 llvm-svn: 300746
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Eli Friedman
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Apr 19, 2017
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; RUN: opt < %s -analyze -scalar-evolution | FileCheck %s | ||
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declare void @z(i32) | ||
declare void @z2(i64) | ||
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define void @fun(i1 %bool, i32 %x) { | ||
entry: | ||
br label %body | ||
body: | ||
%i = phi i32 [ 0, %entry ], [ %i.next, %body ] | ||
%bottom_zero = mul i32 %i, 2 | ||
%a = or i32 %bottom_zero, 1 | ||
call void @z(i32 %a) | ||
%bool_ext = zext i1 %bool to i32 | ||
%b = or i32 %bool_ext, %bottom_zero | ||
call void @z(i32 %b) | ||
%shifted = lshr i32 %x, 31 | ||
%c = or i32 %shifted, %bottom_zero | ||
call void @z(i32 %c) | ||
%i_ext = zext i32 %i to i64 | ||
%d = or i64 %i_ext, 4294967296 | ||
call void @z2(i64 %d) | ||
%i.next = add i32 %i, 1 | ||
%cond = icmp eq i32 %i.next, 10 | ||
br i1 %cond, label %exit, label %body | ||
exit: | ||
ret void | ||
} | ||
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; CHECK: %a = or i32 %bottom_zero, 1 | ||
; CHECK-NEXT: --> {1,+,2}<%body> | ||
; CHECK: %b = or i32 %bool_ext, %bottom_zero | ||
; CHECK-NEXT: --> {(zext i1 %bool to i32),+,2} | ||
; CHECK: %c = or i32 %shifted, %bottom_zero | ||
; CHECK-NEXT: --> {(%x /u -2147483648),+,2}<%body> | ||
; CHECK: %d = or i64 %i_ext, 4294967296 | ||
; CHECK-NEXT: --> {4294967296,+,1}<nuw><nsw><%body> | ||
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