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9a38f41e5e
Add a profitability heuristic to enable runtime unrolling of multi-exit loop: There can be atmost two unique exit blocks for the loop and the second exit block should be a deoptimizing block. Also, there can be one other exiting block other than the latch exiting block. The reason for the latter is so that we limit the number of branches in the unrolled code to being at most the unroll factor. Deoptimizing blocks are rarely taken so these additional number of branches created due to the unrolling are predictable, since one of their target is the deopt block. Reviewers: apilipenko, reames, evstupac, mkuper Subscribers: llvm-commits Reviewed by: reames Differential Revision: https://reviews.llvm.org/D35380 llvm-svn: 313363
95 lines
3.5 KiB
LLVM
95 lines
3.5 KiB
LLVM
; RUN: opt < %s -loop-unroll -unroll-runtime=true -verify-dom-info -verify-loop-info -instcombine -S | FileCheck %s
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; RUN: opt < %s -loop-unroll -unroll-runtime=true -verify-dom-info -unroll-runtime-multi-exit=false -verify-loop-info -S | FileCheck %s -check-prefix=NOUNROLL
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; this tests when unrolling multiple exit loop occurs by default (i.e. without specifying -unroll-runtime-multi-exit)
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; the second exit block is a deopt block. The loop has one exiting block other than the latch.
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define i32 @test1(i32* nocapture %a, i64 %n) {
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; CHECK-LABEL: test1(
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; CHECK-LABEL: header.epil:
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; CHECK-NEXT: %indvars.iv.epil = phi i64 [ %indvars.iv.next.epil, %latch.epil ], [ %indvars.iv.unr, %header.epil.preheader ]
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; CHECK-LABEL: otherexit.loopexit:
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; CHECK-NEXT: %sum.02.lcssa.ph = phi i32 [ %sum.02, %for.exiting_block ], [ %add, %for.exiting_block.1 ], [ %add.1, %for.exiting_block.2 ], [ %add.2, %for.exiting_block.3 ], [ %add.3, %for.exiting_block.4 ], [ %add.4, %for.exiting_block.5 ], [ %add.5, %for.exiting_block.6 ],
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; CHECK-NEXT: br label %otherexit
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; CHECK-LABEL: otherexit.loopexit3:
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; CHECK-NEXT: br label %otherexit
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; CHECK-LABEL: otherexit:
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; CHECK-NEXT: %sum.02.lcssa = phi i32 [ %sum.02.lcssa.ph, %otherexit.loopexit ], [ %sum.02.epil, %otherexit.loopexit3 ]
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; CHECK-NEXT: %rval = call i32 (...) @llvm.experimental.deoptimize.i32() [ "deopt"(i32 %sum.02.lcssa) ]
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; CHECK-NEXT: ret i32 %rval
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; CHECK-LABEL: latch.7:
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; CHECK: add i64 %indvars.iv, 8
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; NOUNROLL: test1(
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; NOUNROLL-NOT: .epil
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; NOUNROLL-NOT: .prol
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; NOUNROLL: otherexit:
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; NOUNROLL-NEXT: %sum.02.lcssa = phi i32 [ %sum.02, %for.exiting_block ]
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; NOUNROLL-NEXT: %rval = call i32 (...) @llvm.experimental.deoptimize.i32() [ "deopt"(i32 %sum.02.lcssa) ]
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entry:
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br label %header
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header:
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%indvars.iv = phi i64 [ %indvars.iv.next, %latch ], [ 0, %entry ]
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%sum.02 = phi i32 [ %add, %latch ], [ 0, %entry ]
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br label %for.exiting_block
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for.exiting_block:
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%cmp = icmp eq i64 %n, 42
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br i1 %cmp, label %otherexit, label %latch
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latch:
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%arrayidx = getelementptr inbounds i32, i32* %a, i64 %indvars.iv
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%0 = load i32, i32* %arrayidx, align 4
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%add = add nsw i32 %0, %sum.02
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%indvars.iv.next = add i64 %indvars.iv, 1
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%exitcond = icmp eq i64 %indvars.iv.next, %n
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br i1 %exitcond, label %latchexit, label %header
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latchexit: ; preds = %latch
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%sum.0.lcssa = phi i32 [ %add, %latch ]
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ret i32 %sum.0.lcssa
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otherexit:
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%rval = call i32(...) @llvm.experimental.deoptimize.i32() [ "deopt"(i32 %sum.02) ]
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ret i32 %rval
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}
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; the exit block is not a deopt block.
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define i32 @test2(i32* nocapture %a, i64 %n) {
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; CHECK-LABEL: test2(
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; CHECK-NOT: .epil
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; CHECK-NOT: .prol
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; CHECK-LABEL: otherexit:
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; CHECK-NEXT: ret i32 %sum.02
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entry:
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br label %header
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header:
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%indvars.iv = phi i64 [ %indvars.iv.next, %latch ], [ 0, %entry ]
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%sum.02 = phi i32 [ %add, %latch ], [ 0, %entry ]
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br label %for.exiting_block
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for.exiting_block:
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%cmp = icmp eq i64 %n, 42
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br i1 %cmp, label %otherexit, label %latch
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latch:
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%arrayidx = getelementptr inbounds i32, i32* %a, i64 %indvars.iv
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%0 = load i32, i32* %arrayidx, align 4
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%add = add nsw i32 %0, %sum.02
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%indvars.iv.next = add i64 %indvars.iv, 1
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%exitcond = icmp eq i64 %indvars.iv.next, %n
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br i1 %exitcond, label %latchexit, label %header
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latchexit: ; preds = %latch
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%sum.0.lcssa = phi i32 [ %add, %latch ]
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ret i32 %sum.0.lcssa
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otherexit:
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%rval = phi i32 [%sum.02, %for.exiting_block ]
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ret i32 %rval
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}
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declare i32 @llvm.experimental.deoptimize.i32(...)
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