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llvm-project/llvm/test/Transforms/LoopPredication/visited.ll

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[Guards] Introduce loop-predication pass This patch introduces guard based loop predication optimization. The new LoopPredication pass tries to convert loop variant range checks to loop invariant by widening checks across loop iterations. For example, it will convert for (i = 0; i < n; i++) { guard(i < len); ... } to for (i = 0; i < n; i++) { guard(n - 1 < len); ... } After this transformation the condition of the guard is loop invariant, so loop-unswitch can later unswitch the loop by this condition which basically predicates the loop by the widened condition: if (n - 1 < len) for (i = 0; i < n; i++) { ... } else deoptimize This patch relies on an NFC change to make ScalarEvolution::isMonotonicPredicate public (revision 293062). Reviewed By: sanjoy Differential Revision: https://reviews.llvm.org/D29034 llvm-svn: 293064
2017-01-26 00:00:44 +08:00
; RUN: opt -S -loop-predication < %s 2>&1 | FileCheck %s
; RUN: opt -S -passes='require<scalar-evolution>,loop(loop-predication)' < %s 2>&1 | FileCheck %s
declare void @llvm.experimental.guard(i1, ...)
define i32 @test_visited(i32* %array, i32 %length, i32 %n, i32 %x) {
; CHECK-LABEL: @test_visited
entry:
%tmp5 = icmp eq i32 %n, 0
br i1 %tmp5, label %exit, label %loop.preheader
loop.preheader:
; CHECK: loop.preheader:
[LoopPredication] Check whether the loop is already guarded by the first iteration check condition llvm-svn: 315623
2017-10-13 05:21:17 +08:00
; CHECK: [[limit_check:[^ ]+]] = icmp ule i32 %n, %length
; CHECK-NEXT: [[first_iteration_check:[^ ]+]] = icmp ult i32 0, %length
Rework loop predication pass We've found a serious issue with the current implementation of loop predication. The current implementation relies on SCEV and this turned out to be problematic. To fix the problem we had to rework the pass substantially. We have had the reworked implementation in our downstream tree for a while. This is the initial patch of the series of changes to upstream the new implementation. For now the transformation is limited to the following case: * The loop has a single latch with either ult or slt icmp condition. * The step of the IV used in the latch condition is 1. * The IV of the latch condition is the same as the post increment IV of the guard condition. * The guard condition is ult. See the review or the LoopPredication.cpp header for the details about the problem and the new implementation. Reviewed By: sanjoy, mkazantsev Differential Revision: https://reviews.llvm.org/D37569 llvm-svn: 313981
2017-09-22 21:13:57 +08:00
; CHECK-NEXT: [[wide_cond:[^ ]+]] = and i1 [[first_iteration_check]], [[limit_check]]
[Guards] Introduce loop-predication pass This patch introduces guard based loop predication optimization. The new LoopPredication pass tries to convert loop variant range checks to loop invariant by widening checks across loop iterations. For example, it will convert for (i = 0; i < n; i++) { guard(i < len); ... } to for (i = 0; i < n; i++) { guard(n - 1 < len); ... } After this transformation the condition of the guard is loop invariant, so loop-unswitch can later unswitch the loop by this condition which basically predicates the loop by the widened condition: if (n - 1 < len) for (i = 0; i < n; i++) { ... } else deoptimize This patch relies on an NFC change to make ScalarEvolution::isMonotonicPredicate public (revision 293062). Reviewed By: sanjoy Differential Revision: https://reviews.llvm.org/D29034 llvm-svn: 293064
2017-01-26 00:00:44 +08:00
; CHECK-NEXT: br label %loop
br label %loop
loop:
; CHECK: loop:
; CHECK: %unrelated.cond = icmp eq i32 %x, %i
; CHECK: [[guard_cond:[^ ]+]] = and i1 %unrelated.cond, [[wide_cond]]
; CHECK-NEXT: call void (i1, ...) @llvm.experimental.guard(i1 [[guard_cond]], i32 9) [ "deopt"() ]
%loop.acc = phi i32 [ %loop.acc.next, %loop ], [ 0, %loop.preheader ]
%i = phi i32 [ %i.next, %loop ], [ 0, %loop.preheader ]
%within.bounds = icmp ult i32 %i, %length
%unrelated.cond = icmp eq i32 %x, %i
%guard.cond.2 = and i1 %within.bounds, %unrelated.cond
%guard.cond.3 = and i1 %guard.cond.2, %unrelated.cond
%guard.cond.4 = and i1 %guard.cond.3, %guard.cond.2
%guard.cond.5 = and i1 %guard.cond.4, %guard.cond.3
%guard.cond.6 = and i1 %guard.cond.5, %guard.cond.4
%guard.cond.7 = and i1 %guard.cond.6, %guard.cond.5
%guard.cond.8 = and i1 %guard.cond.7, %guard.cond.6
%guard.cond.9 = and i1 %guard.cond.8, %guard.cond.7
%guard.cond.10 = and i1 %guard.cond.9, %guard.cond.8
%guard.cond.11 = and i1 %guard.cond.10, %guard.cond.9
%guard.cond.12 = and i1 %guard.cond.11, %guard.cond.10
%guard.cond.13 = and i1 %guard.cond.12, %guard.cond.11
%guard.cond.14 = and i1 %guard.cond.13, %guard.cond.12
%guard.cond.15 = and i1 %guard.cond.14, %guard.cond.13
%guard.cond.16 = and i1 %guard.cond.15, %guard.cond.14
%guard.cond.17 = and i1 %guard.cond.16, %guard.cond.15
%guard.cond.18 = and i1 %guard.cond.17, %guard.cond.16
%guard.cond.19 = and i1 %guard.cond.18, %guard.cond.17
%guard.cond.20 = and i1 %guard.cond.19, %guard.cond.18
%guard.cond.21 = and i1 %guard.cond.20, %guard.cond.19
%guard.cond.22 = and i1 %guard.cond.21, %guard.cond.20
%guard.cond.23 = and i1 %guard.cond.22, %guard.cond.21
%guard.cond.24 = and i1 %guard.cond.23, %guard.cond.22
%guard.cond.25 = and i1 %guard.cond.24, %guard.cond.23
%guard.cond.26 = and i1 %guard.cond.25, %guard.cond.24
%guard.cond.27 = and i1 %guard.cond.26, %guard.cond.25
%guard.cond.28 = and i1 %guard.cond.27, %guard.cond.26
%guard.cond.29 = and i1 %guard.cond.28, %guard.cond.27
%guard.cond.30 = and i1 %guard.cond.29, %guard.cond.28
%guard.cond.31 = and i1 %guard.cond.30, %guard.cond.29
%guard.cond.32 = and i1 %guard.cond.31, %guard.cond.30
%guard.cond.33 = and i1 %guard.cond.32, %guard.cond.31
%guard.cond.34 = and i1 %guard.cond.33, %guard.cond.32
%guard.cond.35 = and i1 %guard.cond.34, %guard.cond.33
%guard.cond.36 = and i1 %guard.cond.35, %guard.cond.34
%guard.cond.37 = and i1 %guard.cond.36, %guard.cond.35
%guard.cond.38 = and i1 %guard.cond.37, %guard.cond.36
%guard.cond.39 = and i1 %guard.cond.38, %guard.cond.37
%guard.cond.40 = and i1 %guard.cond.39, %guard.cond.38
%guard.cond.41 = and i1 %guard.cond.40, %guard.cond.39
%guard.cond.42 = and i1 %guard.cond.41, %guard.cond.40
%guard.cond.43 = and i1 %guard.cond.42, %guard.cond.41
%guard.cond.44 = and i1 %guard.cond.43, %guard.cond.42
%guard.cond.45 = and i1 %guard.cond.44, %guard.cond.43
%guard.cond.46 = and i1 %guard.cond.45, %guard.cond.44
%guard.cond.47 = and i1 %guard.cond.46, %guard.cond.45
%guard.cond.48 = and i1 %guard.cond.47, %guard.cond.46
%guard.cond.49 = and i1 %guard.cond.48, %guard.cond.47
%guard.cond.50 = and i1 %guard.cond.49, %guard.cond.48
%guard.cond.51 = and i1 %guard.cond.50, %guard.cond.49
%guard.cond.52 = and i1 %guard.cond.51, %guard.cond.50
%guard.cond.53 = and i1 %guard.cond.52, %guard.cond.51
%guard.cond.54 = and i1 %guard.cond.53, %guard.cond.52
%guard.cond.55 = and i1 %guard.cond.54, %guard.cond.53
%guard.cond.56 = and i1 %guard.cond.55, %guard.cond.54
%guard.cond.57 = and i1 %guard.cond.56, %guard.cond.55
%guard.cond.58 = and i1 %guard.cond.57, %guard.cond.56
%guard.cond.59 = and i1 %guard.cond.58, %guard.cond.57
%guard.cond.60 = and i1 %guard.cond.59, %guard.cond.58
%guard.cond.61 = and i1 %guard.cond.60, %guard.cond.59
%guard.cond.62 = and i1 %guard.cond.61, %guard.cond.60
%guard.cond.63 = and i1 %guard.cond.62, %guard.cond.61
%guard.cond.64 = and i1 %guard.cond.63, %guard.cond.62
%guard.cond.65 = and i1 %guard.cond.64, %guard.cond.63
%guard.cond.66 = and i1 %guard.cond.65, %guard.cond.64
%guard.cond.67 = and i1 %guard.cond.66, %guard.cond.65
%guard.cond.68 = and i1 %guard.cond.67, %guard.cond.66
%guard.cond.69 = and i1 %guard.cond.68, %guard.cond.67
%guard.cond.70 = and i1 %guard.cond.69, %guard.cond.68
%guard.cond.71 = and i1 %guard.cond.70, %guard.cond.69
%guard.cond.72 = and i1 %guard.cond.71, %guard.cond.70
%guard.cond.73 = and i1 %guard.cond.72, %guard.cond.71
%guard.cond.74 = and i1 %guard.cond.73, %guard.cond.72
%guard.cond.75 = and i1 %guard.cond.74, %guard.cond.73
%guard.cond.76 = and i1 %guard.cond.75, %guard.cond.74
%guard.cond.77 = and i1 %guard.cond.76, %guard.cond.75
%guard.cond.78 = and i1 %guard.cond.77, %guard.cond.76
%guard.cond.79 = and i1 %guard.cond.78, %guard.cond.77
%guard.cond.80 = and i1 %guard.cond.79, %guard.cond.78
%guard.cond.81 = and i1 %guard.cond.80, %guard.cond.79
%guard.cond.82 = and i1 %guard.cond.81, %guard.cond.80
%guard.cond.83 = and i1 %guard.cond.82, %guard.cond.81
%guard.cond.84 = and i1 %guard.cond.83, %guard.cond.82
%guard.cond.85 = and i1 %guard.cond.84, %guard.cond.83
%guard.cond.86 = and i1 %guard.cond.85, %guard.cond.84
%guard.cond.87 = and i1 %guard.cond.86, %guard.cond.85
%guard.cond.88 = and i1 %guard.cond.87, %guard.cond.86
%guard.cond.89 = and i1 %guard.cond.88, %guard.cond.87
%guard.cond.90 = and i1 %guard.cond.89, %guard.cond.88
%guard.cond.91 = and i1 %guard.cond.90, %guard.cond.89
%guard.cond.92 = and i1 %guard.cond.91, %guard.cond.90
%guard.cond.93 = and i1 %guard.cond.92, %guard.cond.91
%guard.cond.94 = and i1 %guard.cond.93, %guard.cond.92
%guard.cond.95 = and i1 %guard.cond.94, %guard.cond.93
%guard.cond.96 = and i1 %guard.cond.95, %guard.cond.94
%guard.cond.97 = and i1 %guard.cond.96, %guard.cond.95
%guard.cond.98 = and i1 %guard.cond.97, %guard.cond.96
%guard.cond.99 = and i1 %guard.cond.98, %guard.cond.97
call void (i1, ...) @llvm.experimental.guard(i1 %guard.cond.99, i32 9) [ "deopt"() ]
%i.i64 = zext i32 %i to i64
%array.i.ptr = getelementptr inbounds i32, i32* %array, i64 %i.i64
%array.i = load i32, i32* %array.i.ptr, align 4
%loop.acc.next = add i32 %loop.acc, %array.i
%i.next = add nuw i32 %i, 1
%continue = icmp ult i32 %i.next, %n
br i1 %continue, label %loop, label %exit
exit:
%result = phi i32 [ 0, %entry ], [ %loop.acc.next, %loop ]
ret i32 %result
}