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https://github.com/RPCS3/llvm-mirror.git
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a8dd5128cf
Splitting a loop to make range checks redundant is profitable only if the range check "never" fails. Make this fact a part of recognizing a range check -- a branch is a range check only if it is expected to pass (via branch_weights metadata). Differential Revision: http://reviews.llvm.org/D7192 llvm-svn: 227249
61 lines
2.3 KiB
LLVM
61 lines
2.3 KiB
LLVM
; RUN: opt -irce -S < %s | FileCheck %s
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define void @single_access_with_preloop(i32 *%arr, i32 *%a_len_ptr, i32 %n, i32 %offset) {
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entry:
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%len = load i32* %a_len_ptr, !range !0
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%first.itr.check = icmp sgt i32 %n, 0
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br i1 %first.itr.check, label %loop, label %exit
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loop:
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%idx = phi i32 [ 0, %entry ] , [ %idx.next, %in.bounds ]
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%idx.next = add i32 %idx, 1
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%array.idx = add i32 %idx, %offset
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%abc.high = icmp slt i32 %array.idx, %len
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%abc.low = icmp sge i32 %array.idx, 0
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%abc = and i1 %abc.low, %abc.high
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br i1 %abc, label %in.bounds, label %out.of.bounds, !prof !1
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in.bounds:
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%addr = getelementptr i32* %arr, i32 %array.idx
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store i32 0, i32* %addr
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%next = icmp slt i32 %idx.next, %n
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br i1 %next, label %loop, label %exit
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out.of.bounds:
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ret void
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exit:
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ret void
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}
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; CHECK-LABEL: loop.preheader:
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; CHECK: [[safe_start:[^ ]+]] = sub i32 0, %offset
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; CHECK: [[safe_end:[^ ]+]] = sub i32 %len, %offset
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; CHECK: [[exit_preloop_at_cond:[^ ]+]] = icmp slt i32 %n, [[safe_start]]
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; CHECK: [[exit_preloop_at:[^ ]+]] = select i1 [[exit_preloop_at_cond]], i32 %n, i32 [[safe_start]]
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; CHECK: [[exit_mainloop_at_cond:[^ ]+]] = icmp slt i32 %n, [[safe_end]]
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; CHECK: [[exit_mainloop_at:[^ ]+]] = select i1 [[exit_mainloop_at_cond]], i32 %n, i32 [[safe_end]]
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; CHECK-LABEL: in.bounds:
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; CHECK: [[continue_mainloop_cond:[^ ]+]] = icmp slt i32 %idx.next, [[exit_mainloop_at]]
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; CHECK: br i1 [[continue_mainloop_cond]], label %loop, label %main.exit.selector
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; CHECK-LABEL: main.exit.selector:
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; CHECK: [[mainloop_its_left:[^ ]+]] = icmp slt i32 %idx.next, %n
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; CHECK: br i1 [[mainloop_its_left]], label %main.pseudo.exit, label %exit.loopexit
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; CHECK-LABEL: in.bounds.preloop:
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; CHECK: [[continue_preloop_cond:[^ ]+]] = icmp slt i32 %idx.next.preloop, [[exit_preloop_at]]
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; CHECK: br i1 [[continue_preloop_cond]], label %loop.preloop, label %preloop.exit.selector
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; CHECK-LABEL: preloop.exit.selector:
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; CHECK: [[preloop_its_left:[^ ]+]] = icmp slt i32 %idx.next.preloop, %n
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; CHECK: br i1 [[preloop_its_left]], label %preloop.pseudo.exit, label %exit.loopexit
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; CHECK-LABEL: in.bounds.postloop:
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; CHECK: %next.postloop = icmp slt i32 %idx.next.postloop, %n
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; CHECK: br i1 %next.postloop, label %loop.postloop, label %exit.loopexit
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!0 = !{i32 0, i32 2147483647}
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!1 = !{!"branch_weights", i32 64, i32 4}
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