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https://github.com/c64scene-ar/llvm-6502.git
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eb9a42e8ab
- it is trivially known to be used inside the loop in a way that can not be optimized away - there is no use outside of the loop which can take advantage of the computation hoisting git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@177432 91177308-0d34-0410-b5e6-96231b3b80d8
70 lines
2.0 KiB
LLVM
70 lines
2.0 KiB
LLVM
; RUN: opt < %s -indvars -S | FileCheck %s
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; This tests that the IV is not recomputed outside of the loop when it is known
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; to be computed by the loop and used in the loop any way. In the example below
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; although a's value can be computed outside of the loop, there is no benefit
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; in doing so as it has to be computed by the loop anyway.
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;
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; extern void func(unsigned val);
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;
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; void test(unsigned m)
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; {
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; unsigned a = 0;
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;
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; for (int i=0; i<186; i++) {
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; a += m;
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; func(a);
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; }
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;
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; func(a);
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; }
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declare void @func(i32)
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; CHECK: @test
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define void @test(i32 %m) nounwind uwtable {
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entry:
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br label %for.body
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for.body: ; preds = %for.body, %entry
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%i.06 = phi i32 [ 0, %entry ], [ %inc, %for.body ]
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%a.05 = phi i32 [ 0, %entry ], [ %add, %for.body ]
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%add = add i32 %a.05, %m
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; CHECK: tail call void @func(i32 %add)
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tail call void @func(i32 %add)
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%inc = add nsw i32 %i.06, 1
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%exitcond = icmp eq i32 %inc, 186
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br i1 %exitcond, label %for.end, label %for.body
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for.end: ; preds = %for.body
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; CHECK: for.end:
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; CHECK-NOT: mul i32 %m, 186
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; CHECK:%add.lcssa = phi i32 [ %add, %for.body ]
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; CHECK-NEXT: tail call void @func(i32 %add.lcssa)
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tail call void @func(i32 %add)
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ret void
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}
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; CHECK: @test2
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define i32 @test2(i32 %m) nounwind uwtable {
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entry:
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br label %for.body
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for.body: ; preds = %for.body, %entry
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%i.06 = phi i32 [ 0, %entry ], [ %inc, %for.body ]
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%a.05 = phi i32 [ 0, %entry ], [ %add, %for.body ]
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%add = add i32 %a.05, %m
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; CHECK: tail call void @func(i32 %add)
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tail call void @func(i32 %add)
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%inc = add nsw i32 %i.06, 1
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%exitcond = icmp eq i32 %inc, 186
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br i1 %exitcond, label %for.end, label %for.body
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for.end: ; preds = %for.body
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; CHECK: for.end:
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; CHECK-NOT: mul i32 %m, 186
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; CHECK:%add.lcssa = phi i32 [ %add, %for.body ]
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; CHECK-NEXT: ret i32 %add.lcssa
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ret i32 %add
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}
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