mirror of
https://github.com/RPCS3/llvm.git
synced 2025-05-15 01:46:46 +00:00
788841cb66
Summary: When simplifying unconditional branches from empty blocks, we pre-test if the BB belongs to a set of loop headers and keep the block to prevent passes from destroying canonical loop structure. However, the current algorithm fails if the destination of the branch is a loop header. Especially when such a loop's latch block is folded into loop header it results in additional backedges and LoopSimplify turns it into a nested loop which prevent later optimizations from being applied (e.g., loop unrolling and loop interleaving). This patch augments the existing algorithm by further checking if the destination of the branch belongs to a set of loop headers and defer eliminating it if yes to LateSimplifyCFG. Fixes PR33605: https://bugs.llvm.org/show_bug.cgi?id=33605 Reviewers: efriedma, mcrosier, pacxx, hsung, davidxl Reviewed By: efriedma Subscribers: ashutosh.nema, gberry, javed.absar, llvm-commits Differential Revision: https://reviews.llvm.org/D35411 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@308422 91177308-0d34-0410-b5e6-96231b3b80d8
101 lines
4.1 KiB
LLVM
101 lines
4.1 KiB
LLVM
; RUN: opt < %s -S -loop-unroll -unroll-force-peel-count=3 -verify-dom-info -simplifycfg -instcombine | FileCheck %s
|
|
|
|
; Basic loop peeling - check that we can peel-off the first 3 loop iterations
|
|
; when explicitly requested.
|
|
; CHECK-LABEL: @basic
|
|
; CHECK: %[[CMP0:.*]] = icmp sgt i32 %k, 0
|
|
; CHECK: br i1 %[[CMP0]], label %[[NEXT0:.*]], label %for.end
|
|
; CHECK: [[NEXT0]]:
|
|
; CHECK: store i32 0, i32* %p, align 4
|
|
; CHECK: %[[CMP1:.*]] = icmp eq i32 %k, 1
|
|
; CHECK: br i1 %[[CMP1]], label %for.end, label %[[NEXT1:.*]]
|
|
; CHECK: [[NEXT1]]:
|
|
; CHECK: %[[INC1:.*]] = getelementptr inbounds i32, i32* %p, i64 1
|
|
; CHECK: store i32 1, i32* %[[INC1]], align 4
|
|
; CHECK: %[[CMP2:.*]] = icmp sgt i32 %k, 2
|
|
; CHECK: br i1 %[[CMP2]], label %[[NEXT2:.*]], label %for.end
|
|
; CHECK: [[NEXT2]]:
|
|
; CHECK: %[[INC2:.*]] = getelementptr inbounds i32, i32* %p, i64 2
|
|
; CHECK: store i32 2, i32* %[[INC2]], align 4
|
|
; CHECK: %[[CMP3:.*]] = icmp eq i32 %k, 3
|
|
; CHECK: br i1 %[[CMP3]], label %for.end, label %[[LOOP_PH:.*]]
|
|
; CHECK: [[LOOP_PH]]:
|
|
; CHECK: br label %[[LOOP:.*]]
|
|
; CHECK: [[LOOP]]:
|
|
; CHECK: %[[IV:.*]] = phi i32 [ 3, %[[LOOP_PH]] ], [ {{.*}}, %[[LOOP]] ]
|
|
|
|
define void @basic(i32* %p, i32 %k) #0 {
|
|
entry:
|
|
%cmp3 = icmp slt i32 0, %k
|
|
br i1 %cmp3, label %for.body.lr.ph, label %for.end
|
|
|
|
for.body.lr.ph: ; preds = %entry
|
|
br label %for.body
|
|
|
|
for.body: ; preds = %for.body.lr.ph, %for.body
|
|
%i.05 = phi i32 [ 0, %for.body.lr.ph ], [ %inc, %for.body ]
|
|
%p.addr.04 = phi i32* [ %p, %for.body.lr.ph ], [ %incdec.ptr, %for.body ]
|
|
%incdec.ptr = getelementptr inbounds i32, i32* %p.addr.04, i32 1
|
|
store i32 %i.05, i32* %p.addr.04, align 4
|
|
%inc = add nsw i32 %i.05, 1
|
|
%cmp = icmp slt i32 %inc, %k
|
|
br i1 %cmp, label %for.body, label %for.cond.for.end_crit_edge
|
|
|
|
for.cond.for.end_crit_edge: ; preds = %for.body
|
|
br label %for.end
|
|
|
|
for.end: ; preds = %for.cond.for.end_crit_edge, %entry
|
|
ret void
|
|
}
|
|
|
|
; Make sure peeling works correctly when a value defined in a loop is used
|
|
; in later code - we need to correctly plumb the phi depending on which
|
|
; iteration is actually used.
|
|
; CHECK-LABEL: @output
|
|
; CHECK: %[[CMP0:.*]] = icmp sgt i32 %k, 0
|
|
; CHECK: br i1 %[[CMP0]], label %[[NEXT0:.*]], label %for.end
|
|
; CHECK: [[NEXT0]]:
|
|
; CHECK: store i32 0, i32* %p, align 4
|
|
; CHECK: %[[CMP1:.*]] = icmp eq i32 %k, 1
|
|
; CHECK: br i1 %[[CMP1]], label %for.end, label %[[NEXT1:.*]]
|
|
; CHECK: [[NEXT1]]:
|
|
; CHECK: %[[INC1:.*]] = getelementptr inbounds i32, i32* %p, i64 1
|
|
; CHECK: store i32 1, i32* %[[INC1]], align 4
|
|
; CHECK: %[[CMP2:.*]] = icmp sgt i32 %k, 2
|
|
; CHECK: br i1 %[[CMP2]], label %[[NEXT2:.*]], label %for.end
|
|
; CHECK: [[NEXT2]]:
|
|
; CHECK: %[[INC2:.*]] = getelementptr inbounds i32, i32* %p, i64 2
|
|
; CHECK: store i32 2, i32* %[[INC2]], align 4
|
|
; CHECK: %[[CMP3:.*]] = icmp eq i32 %k, 3
|
|
; CHECK: br i1 %[[CMP3]], label %for.end, label %[[LOOP_PH:.*]]
|
|
; CHECK: [[LOOP_PH]]:
|
|
; CHECK: br label %[[LOOP:.*]]
|
|
; CHECK: [[LOOP]]:
|
|
; CHECK: %[[IV:.*]] = phi i32 [ 3, %[[LOOP_PH]] ], [ %[[IV:.*]], %[[LOOP]] ]
|
|
; CHECK: %ret = phi i32 [ 0, %entry ], [ 1, %[[NEXT0]] ], [ 2, %[[NEXT1]] ], [ 3, %[[NEXT2]] ], [ %[[IV]], %[[LOOP]] ]
|
|
; CHECK: ret i32 %ret
|
|
define i32 @output(i32* %p, i32 %k) #0 {
|
|
entry:
|
|
%cmp3 = icmp slt i32 0, %k
|
|
br i1 %cmp3, label %for.body.lr.ph, label %for.end
|
|
|
|
for.body.lr.ph: ; preds = %entry
|
|
br label %for.body
|
|
|
|
for.body: ; preds = %for.body.lr.ph, %for.body
|
|
%i.05 = phi i32 [ 0, %for.body.lr.ph ], [ %inc, %for.body ]
|
|
%p.addr.04 = phi i32* [ %p, %for.body.lr.ph ], [ %incdec.ptr, %for.body ]
|
|
%incdec.ptr = getelementptr inbounds i32, i32* %p.addr.04, i32 1
|
|
store i32 %i.05, i32* %p.addr.04, align 4
|
|
%inc = add nsw i32 %i.05, 1
|
|
%cmp = icmp slt i32 %inc, %k
|
|
br i1 %cmp, label %for.body, label %for.cond.for.end_crit_edge
|
|
|
|
for.cond.for.end_crit_edge: ; preds = %for.body
|
|
br label %for.end
|
|
|
|
for.end: ; preds = %for.cond.for.end_crit_edge, %entry
|
|
%ret = phi i32 [ 0, %entry], [ %inc, %for.cond.for.end_crit_edge ]
|
|
ret i32 %ret
|
|
}
|