[AArch64][Falkor] Try to avoid exhausting HW prefetcher resources when unrolling.

Reviewers: t.p.northover, mcrosier

Subscribers: aemerson, rengolin, javed.absar, kristof.beyls, llvm-commits

Differential Revision: https://reviews.llvm.org/D34533

llvm-svn: 306584

1 files changed, 169 insertions, 0 deletions

diff --git a/llvm/test/Transforms/LoopUnroll/AArch64/falkor-prefetch.ll b/llvm/test/Transforms/LoopUnroll/AArch64/falkor-prefetch.ll
new file mode 100644
index 00000000000..b2930dc5f89
--- /dev/null
+++ b/llvm/test/Transforms/LoopUnroll/AArch64/falkor-prefetch.ll
@@ -0,0 +1,169 @@
+; RUN: opt < %s -S -loop-unroll -mtriple aarch64 -mcpu=falkor | FileCheck %s
+; RUN: opt < %s -S -loop-unroll -mtriple aarch64 -mcpu=falkor -enable-falkor-hwpf-unroll-fix=0 | FileCheck %s --check-prefix=NOHWPF
+
+; Check that loop unroller doesn't exhaust HW prefetcher resources.
+
+; Partial unroll 2 times for this loop on falkor instead of 4.
+; NOHWPF-LABEL: @unroll1(
+; NOHWPF-LABEL: loop:
+; NOHWPF-NEXT: phi
+; NOHWPF-NEXT: getelementptr
+; NOHWPF-NEXT: load
+; NOHWPF-NEXT: getelementptr
+; NOHWPF-NEXT: load
+; NOHWPF-NEXT: add
+; NOHWPF-NEXT: getelementptr
+; NOHWPF-NEXT: load
+; NOHWPF-NEXT: getelementptr
+; NOHWPF-NEXT: load
+; NOHWPF-NEXT: add
+; NOHWPF-NEXT: getelementptr
+; NOHWPF-NEXT: load
+; NOHWPF-NEXT: getelementptr
+; NOHWPF-NEXT: load
+; NOHWPF-NEXT: add
+; NOHWPF-NEXT: getelementptr
+; NOHWPF-NEXT: load
+; NOHWPF-NEXT: getelementptr
+; NOHWPF-NEXT: load
+; NOHWPF-NEXT: add
+; NOHWPF-NEXT: icmp
+; NOHWPF-NEXT: br
+; NOHWPF-NEXT-LABEL: exit:
+;
+; CHECK-LABEL: @unroll1(
+; CHECK-LABEL: loop:
+; CHECK-NEXT: phi
+; CHECK-NEXT: getelementptr
+; CHECK-NEXT: load
+; CHECK-NEXT: getelementptr
+; CHECK-NEXT: load
+; CHECK-NEXT: add
+; CHECK-NEXT: getelementptr
+; CHECK-NEXT: load
+; CHECK-NEXT: getelementptr
+; CHECK-NEXT: load
+; CHECK-NEXT: add
+; CHECK-NEXT: icmp
+; CHECK-NEXT: br
+; CHECK-NEXT-LABEL: exit:
+define void @unroll1(i32* %p, i32* %p2) {
+entry:
+  br label %loop
+
+loop:
+  %iv = phi i32 [ 0, %entry ], [ %inc, %loop ]
+
+  %gep = getelementptr inbounds i32, i32* %p, i32 %iv
+  %load = load volatile i32, i32* %gep
+
+  %gep2 = getelementptr inbounds i32, i32* %p2, i32 %iv
+  %load2 = load volatile i32, i32* %gep2
+
+  %inc = add i32 %iv, 1
+  %exitcnd = icmp uge i32 %inc, 1024
+  br i1 %exitcnd, label %exit, label %loop
+
+exit:
+  ret void
+}
+
+; Partial unroll 4 times for this loop on falkor instead of 8.
+; NOHWPF-LABEL: @unroll2(
+; NOHWPF-LABEL: loop2:
+; NOHWPF-NEXT: phi
+; NOHWPF-NEXT: phi
+; NOHWPF-NEXT: getelementptr
+; NOHWPF-NEXT: load
+; NOHWPF-NEXT: add
+; NOHWPF-NEXT: add
+; NOHWPF-NEXT: getelementptr
+; NOHWPF-NEXT: load
+; NOHWPF-NEXT: add
+; NOHWPF-NEXT: add
+; NOHWPF-NEXT: getelementptr
+; NOHWPF-NEXT: load
+; NOHWPF-NEXT: add
+; NOHWPF-NEXT: add
+; NOHWPF-NEXT: getelementptr
+; NOHWPF-NEXT: load
+; NOHWPF-NEXT: add
+; NOHWPF-NEXT: add
+; NOHWPF-NEXT: getelementptr
+; NOHWPF-NEXT: load
+; NOHWPF-NEXT: add
+; NOHWPF-NEXT: add
+; NOHWPF-NEXT: getelementptr
+; NOHWPF-NEXT: load
+; NOHWPF-NEXT: add
+; NOHWPF-NEXT: add
+; NOHWPF-NEXT: getelementptr
+; NOHWPF-NEXT: load
+; NOHWPF-NEXT: add
+; NOHWPF-NEXT: add
+; NOHWPF-NEXT: getelementptr
+; NOHWPF-NEXT: load
+; NOHWPF-NEXT: add
+; NOHWPF-NEXT: add
+; NOHWPF-NEXT: icmp
+; NOHWPF-NEXT: br
+; NOHWPF-NEXT-LABEL: exit2:
+;
+; CHECK-LABEL: @unroll2(
+; CHECK-LABEL: loop2:
+; CHECK-NEXT: phi
+; CHECK-NEXT: phi
+; CHECK-NEXT: getelementptr
+; CHECK-NEXT: load
+; CHECK-NEXT: add
+; CHECK-NEXT: add
+; CHECK-NEXT: getelementptr
+; CHECK-NEXT: load
+; CHECK-NEXT: add
+; CHECK-NEXT: add
+; CHECK-NEXT: getelementptr
+; CHECK-NEXT: load
+; CHECK-NEXT: add
+; CHECK-NEXT: add
+; CHECK-NEXT: getelementptr
+; CHECK-NEXT: load
+; CHECK-NEXT: add
+; CHECK-NEXT: add
+; CHECK-NEXT: icmp
+; CHECK-NEXT: br
+; CHECK-NEXT-LABEL: exit2:
+
+define void @unroll2(i32* %p) {
+entry:
+  br label %loop1
+
+loop1:
+  %iv1 = phi i32 [ 0, %entry ], [ %inc1, %loop1.latch ]
+  %outer.sum = phi i32 [ 0, %entry ], [ %sum, %loop1.latch ]
+  br label %loop2.header
+
+loop2.header:
+  br label %loop2
+
+loop2:
+  %iv2 = phi i32 [ 0, %loop2.header ], [ %inc2, %loop2 ]
+  %sum = phi i32 [ %outer.sum, %loop2.header ], [ %sum.inc, %loop2 ]
+  %gep = getelementptr inbounds i32, i32* %p, i32 %iv2
+  %load = load i32, i32* %gep
+  %sum.inc = add i32 %sum, %load
+  %inc2 = add i32 %iv2, 1
+  %exitcnd2 = icmp uge i32 %inc2, 1024
+  br i1 %exitcnd2, label %exit2, label %loop2
+
+exit2:
+  br label %loop1.latch
+
+loop1.latch:
+  %inc1 = add i32 %iv1, 1
+  %exitcnd1 = icmp uge i32 %inc1, 1024
+  br i1 %exitcnd2, label %exit, label %loop1
+
+exit:
+  ret void
+}
+