66182d6c38
The commit rL308422 introduces a restriction for folding unconditional branches. Specifically if empty block with unconditional branch leads to header of the loop then elimination of this basic block is prohibited. However it seems this condition is redundantly strict. If elimination of this basic block does not introduce more back edges then we can eliminate this block. The patch implements this relax of restriction. The test profile/Linux/counter_promo_nest.c in compiler-rt project is updated to meet this change. Reviewers: efriedma, mcrosier, pacxx, hsung, davidxl Reviewed By: pacxx Subscribers: llvm-commits Differential Revision: https://reviews.llvm.org/D42691 llvm-svn: 324572
96 lines
3.9 KiB
LLVM
96 lines
3.9 KiB
LLVM
; RUN: opt < %s -S -loop-unroll -unroll-force-peel-count=3 -verify-dom-info -simplifycfg -instcombine | FileCheck %s
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; Basic loop peeling - check that we can peel-off the first 3 loop iterations
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; when explicitly requested.
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; CHECK-LABEL: @basic
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; CHECK: %[[CMP0:.*]] = icmp sgt i32 %k, 0
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; CHECK: br i1 %[[CMP0]], label %[[NEXT0:.*]], label %for.end
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; CHECK: [[NEXT0]]:
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; CHECK: store i32 0, i32* %p, align 4
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; CHECK: %[[CMP1:.*]] = icmp eq i32 %k, 1
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; CHECK: br i1 %[[CMP1]], label %for.end, label %[[NEXT1:.*]]
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; CHECK: [[NEXT1]]:
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; CHECK: %[[INC1:.*]] = getelementptr inbounds i32, i32* %p, i64 1
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; CHECK: store i32 1, i32* %[[INC1]], align 4
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; CHECK: %[[CMP2:.*]] = icmp sgt i32 %k, 2
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; CHECK: br i1 %[[CMP2]], label %[[NEXT2:.*]], label %for.end
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; CHECK: [[NEXT2]]:
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; CHECK: %[[INC2:.*]] = getelementptr inbounds i32, i32* %p, i64 2
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; CHECK: store i32 2, i32* %[[INC2]], align 4
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; CHECK: %[[CMP3:.*]] = icmp eq i32 %k, 3
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; CHECK: br i1 %[[CMP3]], label %for.end, label %[[LOOP_PH:.*]]
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; CHECK: for.end:
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; CHECK: ret void
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define void @basic(i32* %p, i32 %k) #0 {
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entry:
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%cmp3 = icmp slt i32 0, %k
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br i1 %cmp3, label %for.body.lr.ph, label %for.end
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for.body.lr.ph: ; preds = %entry
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br label %for.body
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for.body: ; preds = %for.body.lr.ph, %for.body
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%i.05 = phi i32 [ 0, %for.body.lr.ph ], [ %inc, %for.body ]
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%p.addr.04 = phi i32* [ %p, %for.body.lr.ph ], [ %incdec.ptr, %for.body ]
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%incdec.ptr = getelementptr inbounds i32, i32* %p.addr.04, i32 1
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store i32 %i.05, i32* %p.addr.04, align 4
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%inc = add nsw i32 %i.05, 1
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%cmp = icmp slt i32 %inc, %k
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br i1 %cmp, label %for.body, label %for.cond.for.end_crit_edge
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for.cond.for.end_crit_edge: ; preds = %for.body
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br label %for.end
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for.end: ; preds = %for.cond.for.end_crit_edge, %entry
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ret void
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}
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; Make sure peeling works correctly when a value defined in a loop is used
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; in later code - we need to correctly plumb the phi depending on which
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; iteration is actually used.
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; CHECK-LABEL: @output
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; CHECK: %[[CMP0:.*]] = icmp sgt i32 %k, 0
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; CHECK: br i1 %[[CMP0]], label %[[NEXT0:.*]], label %for.end
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; CHECK: [[NEXT0]]:
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; CHECK: store i32 0, i32* %p, align 4
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; CHECK: %[[CMP1:.*]] = icmp eq i32 %k, 1
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; CHECK: br i1 %[[CMP1]], label %for.end, label %[[NEXT1:.*]]
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; CHECK: [[NEXT1]]:
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; CHECK: %[[INC1:.*]] = getelementptr inbounds i32, i32* %p, i64 1
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; CHECK: store i32 1, i32* %[[INC1]], align 4
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; CHECK: %[[CMP2:.*]] = icmp sgt i32 %k, 2
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; CHECK: br i1 %[[CMP2]], label %[[NEXT2:.*]], label %for.end
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; CHECK: [[NEXT2]]:
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; CHECK: %[[INC2:.*]] = getelementptr inbounds i32, i32* %p, i64 2
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; CHECK: store i32 2, i32* %[[INC2]], align 4
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; CHECK: %[[CMP3:.*]] = icmp eq i32 %k, 3
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; CHECK: br i1 %[[CMP3]], label %for.end, label %[[LOOP_PH:.*]]
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; CHECK: for.end:
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; CHECK: %ret = phi i32 [ 0, %entry ], [ 1, %[[NEXT0]] ], [ 2, %[[NEXT1]] ], [ 3, %[[NEXT2]] ], [ %inc, %for.body ]
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; CHECK: ret i32 %ret
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define i32 @output(i32* %p, i32 %k) #0 {
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entry:
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%cmp3 = icmp slt i32 0, %k
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br i1 %cmp3, label %for.body.lr.ph, label %for.end
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for.body.lr.ph: ; preds = %entry
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br label %for.body
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for.body: ; preds = %for.body.lr.ph, %for.body
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%i.05 = phi i32 [ 0, %for.body.lr.ph ], [ %inc, %for.body ]
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%p.addr.04 = phi i32* [ %p, %for.body.lr.ph ], [ %incdec.ptr, %for.body ]
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%incdec.ptr = getelementptr inbounds i32, i32* %p.addr.04, i32 1
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store i32 %i.05, i32* %p.addr.04, align 4
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%inc = add nsw i32 %i.05, 1
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%cmp = icmp slt i32 %inc, %k
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br i1 %cmp, label %for.body, label %for.cond.for.end_crit_edge
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for.cond.for.end_crit_edge: ; preds = %for.body
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br label %for.end
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for.end: ; preds = %for.cond.for.end_crit_edge, %entry
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%ret = phi i32 [ 0, %entry], [ %inc, %for.cond.for.end_crit_edge ]
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ret i32 %ret
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}
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