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https://github.com/c64scene-ar/llvm-6502.git
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cabfea2a58
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@81540 91177308-0d34-0410-b5e6-96231b3b80d8
102 lines
3.2 KiB
LLVM
102 lines
3.2 KiB
LLVM
; RUN: opt < %s -tailcallelim -S | not grep call
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; PR4323
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; Several cases where tail call elimination should move the load above the call,
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; then eliminate the tail recursion.
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@global = external global i32 ; <i32*> [#uses=1]
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@extern_weak_global = extern_weak global i32 ; <i32*> [#uses=1]
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; This load can be moved above the call because the function won't write to it
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; and the call has no side effects.
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define fastcc i32 @raise_load_1(i32* %a_arg, i32 %a_len_arg, i32 %start_arg) nounwind readonly {
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entry:
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%tmp2 = icmp sge i32 %start_arg, %a_len_arg ; <i1> [#uses=1]
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br i1 %tmp2, label %if, label %else
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if: ; preds = %entry
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ret i32 0
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else: ; preds = %entry
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%tmp7 = add i32 %start_arg, 1 ; <i32> [#uses=1]
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%tmp8 = call fastcc i32 @raise_load_1(i32* %a_arg, i32 %a_len_arg, i32 %tmp7) ; <i32> [#uses=1]
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%tmp9 = load i32* %a_arg ; <i32> [#uses=1]
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%tmp10 = add i32 %tmp9, %tmp8 ; <i32> [#uses=1]
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ret i32 %tmp10
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}
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; This load can be moved above the call because the function won't write to it
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; and the load provably can't trap.
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define fastcc i32 @raise_load_2(i32* %a_arg, i32 %a_len_arg, i32 %start_arg) readonly {
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entry:
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%tmp2 = icmp sge i32 %start_arg, %a_len_arg ; <i1> [#uses=1]
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br i1 %tmp2, label %if, label %else
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if: ; preds = %entry
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ret i32 0
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else: ; preds = %entry
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%nullcheck = icmp eq i32* %a_arg, null ; <i1> [#uses=1]
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br i1 %nullcheck, label %unwind, label %recurse
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unwind: ; preds = %else
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unwind
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recurse: ; preds = %else
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%tmp7 = add i32 %start_arg, 1 ; <i32> [#uses=1]
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%tmp8 = call fastcc i32 @raise_load_2(i32* %a_arg, i32 %a_len_arg, i32 %tmp7) ; <i32> [#uses=1]
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%tmp9 = load i32* @global ; <i32> [#uses=1]
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%tmp10 = add i32 %tmp9, %tmp8 ; <i32> [#uses=1]
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ret i32 %tmp10
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}
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; This load can be safely moved above the call (even though it's from an
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; extern_weak global) because the call has no side effects.
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define fastcc i32 @raise_load_3(i32* %a_arg, i32 %a_len_arg, i32 %start_arg) nounwind readonly {
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entry:
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%tmp2 = icmp sge i32 %start_arg, %a_len_arg ; <i1> [#uses=1]
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br i1 %tmp2, label %if, label %else
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if: ; preds = %entry
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ret i32 0
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else: ; preds = %entry
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%tmp7 = add i32 %start_arg, 1 ; <i32> [#uses=1]
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%tmp8 = call fastcc i32 @raise_load_3(i32* %a_arg, i32 %a_len_arg, i32 %tmp7) ; <i32> [#uses=1]
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%tmp9 = load i32* @extern_weak_global ; <i32> [#uses=1]
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%tmp10 = add i32 %tmp9, %tmp8 ; <i32> [#uses=1]
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ret i32 %tmp10
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}
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; The second load can be safely moved above the call even though it's from an
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; unknown pointer (which normally means it might trap) because the first load
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; proves it doesn't trap.
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define fastcc i32 @raise_load_4(i32* %a_arg, i32 %a_len_arg, i32 %start_arg) readonly {
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entry:
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%tmp2 = icmp sge i32 %start_arg, %a_len_arg ; <i1> [#uses=1]
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br i1 %tmp2, label %if, label %else
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if: ; preds = %entry
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ret i32 0
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else: ; preds = %entry
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%nullcheck = icmp eq i32* %a_arg, null ; <i1> [#uses=1]
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br i1 %nullcheck, label %unwind, label %recurse
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unwind: ; preds = %else
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unwind
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recurse: ; preds = %else
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%tmp7 = add i32 %start_arg, 1 ; <i32> [#uses=1]
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%first = load i32* %a_arg ; <i32> [#uses=1]
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%tmp8 = call fastcc i32 @raise_load_4(i32* %a_arg, i32 %first, i32 %tmp7) ; <i32> [#uses=1]
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%second = load i32* %a_arg ; <i32> [#uses=1]
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%tmp10 = add i32 %second, %tmp8 ; <i32> [#uses=1]
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ret i32 %tmp10
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}
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