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https://github.com/c64scene-ar/llvm-6502.git
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3d03d60ca8
This adds a set of utility functions for collecting 'ephemeral' values. These are LLVM IR values that are used only by @llvm.assume intrinsics (directly or indirectly), and thus will be removed prior to code generation, implying that they should be considered free for certain purposes (like inlining). The inliner's cost analysis, and a few other passes, have been updated to account for ephemeral values using the provided functionality. This functionality is important for the usability of @llvm.assume, because it limits the "non-local" side-effects of adding llvm.assume on inlining, loop unrolling, etc. (these are hints, and do not generate code, so they should not directly contribute to estimates of execution cost). git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@217335 91177308-0d34-0410-b5e6-96231b3b80d8
45 lines
1.3 KiB
LLVM
45 lines
1.3 KiB
LLVM
; RUN: opt < %s -S -loop-unroll -unroll-threshold=50 | FileCheck %s
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; Make sure this loop is completely unrolled...
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; CHECK-LABEL: @test1
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; CHECK: for.body:
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; CHECK-NOT: for.end:
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define i32 @test1(i32* nocapture %a) nounwind uwtable readonly {
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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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%indvars.iv = phi i64 [ 0, %entry ], [ %indvars.iv.next, %for.body ]
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%sum.01 = phi i32 [ 0, %entry ], [ %add, %for.body ]
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%arrayidx = getelementptr inbounds i32* %a, i64 %indvars.iv
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%0 = load i32* %arrayidx, align 4
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; This loop will be completely unrolled, even with these extra instructions,
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; but only because they're ephemeral (and, thus, free).
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%1 = add nsw i32 %0, 2
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%2 = add nsw i32 %1, 4
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%3 = add nsw i32 %2, 4
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%4 = add nsw i32 %3, 4
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%5 = add nsw i32 %4, 4
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%6 = add nsw i32 %5, 4
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%7 = add nsw i32 %6, 4
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%8 = add nsw i32 %7, 4
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%9 = add nsw i32 %8, 4
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%10 = add nsw i32 %9, 4
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%ca = icmp sgt i32 %10, -7
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call void @llvm.assume(i1 %ca)
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%add = add nsw i32 %0, %sum.01
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%indvars.iv.next = add i64 %indvars.iv, 1
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%lftr.wideiv = trunc i64 %indvars.iv.next to i32
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%exitcond = icmp eq i32 %lftr.wideiv, 5
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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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ret i32 %add
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}
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declare void @llvm.assume(i1) nounwind
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