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llvm-mirror/test/CodeGen/Hexagon/swp-copytophi-dag.ll
James Molloy 25cc728d30 [ModuloSchedule] Peel out prologs and epilogs, generate actual code
Summary:
This extends the PeelingModuloScheduleExpander to generate prolog and epilog code,
and correctly stitch uses through the prolog, kernel, epilog DAG.

The key concept in this patch is to ensure that all transforms are *local*; only a
function of a block and its immediate predecessor and successor. By defining the problem in this way
we can inductively rewrite the entire DAG using only local knowledge that is easy to
reason about.

For example, we assume that all prologs and epilogs are near-perfect clones of the
steady-state kernel. This means that if a block has an instruction that is predicated out,
we can redirect all users of that instruction to that equivalent instruction in our
immediate predecessor. As all blocks are clones, every instruction must have an equivalent in
every other block.

Similarly we can make the assumption by construction that if a value defined in a block is used
outside that block, the only possible user is its immediate successors. We maintain this
even for values that are used outside the loop by creating a limited form of LCSSA.

This code isn't small, but it isn't complex.

Enabled a bunch of testing from Hexagon. There are a couple of tests not enabled yet;
I'm about 80% sure there isn't buggy codegen but the tests are checking for patterns
that we don't produce. Those still need a bit more investigation. In the meantime we
(Google) are happy with the code produced by this on our downstream SMS implementation,
and believe it generates correct code.

Subscribers: mgorny, hiraditya, jsji, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D68205

llvm-svn: 373462
2019-10-02 12:46:44 +00:00

75 lines
3.9 KiB
LLVM

; REQUIRES: asserts
;
; RUN: llc -march=hexagon -enable-pipeliner=true -debug-only=pipeliner < %s \
; RUN: 2>&1 -pipeliner-experimental-cg=true | FileCheck %s
; Test that the artificial dependence is created as a result of
; CopyToPhi DAG mutation.
; CHECK: Ord Latency=0 Artificial
target triple = "hexagon"
; Function Attrs: nounwind
define void @foo(i64* nocapture readonly %r64, i16 zeroext %n, i16 zeroext %s, i64* nocapture %p64) #0 {
entry:
%conv = zext i16 %n to i32
%cmp = icmp eq i16 %n, 0
br i1 %cmp, label %for.end, label %for.body.preheader
for.body.preheader: ; preds = %entry
%tmp = load i64, i64* %r64, align 8
%v.sroa.0.0.extract.trunc = trunc i64 %tmp to i16
%v.sroa.4.0.extract.shift = lshr i64 %tmp, 16
%v.sroa.4.0.extract.trunc = trunc i64 %v.sroa.4.0.extract.shift to i16
%v.sroa.5.0.extract.shift = lshr i64 %tmp, 32
%v.sroa.5.0.extract.trunc = trunc i64 %v.sroa.5.0.extract.shift to i16
%v.sroa.6.0.extract.shift = lshr i64 %tmp, 48
%v.sroa.6.0.extract.trunc = trunc i64 %v.sroa.6.0.extract.shift to i16
%tmp1 = bitcast i64* %p64 to i16*
%conv2 = zext i16 %s to i32
%add.ptr = getelementptr inbounds i16, i16* %tmp1, i32 %conv2
%add.ptr.sum = add nuw nsw i32 %conv2, 1
%add.ptr3 = getelementptr inbounds i16, i16* %tmp1, i32 %add.ptr.sum
%add.ptr.sum50 = add nuw nsw i32 %conv2, 2
%add.ptr4 = getelementptr inbounds i16, i16* %tmp1, i32 %add.ptr.sum50
%add.ptr.sum51 = add nuw nsw i32 %conv2, 3
%add.ptr5 = getelementptr inbounds i16, i16* %tmp1, i32 %add.ptr.sum51
br label %for.body
for.body: ; preds = %for.body, %for.body.preheader
%add.ptr11.phi = phi i16* [ %add.ptr11.inc, %for.body ], [ %add.ptr, %for.body.preheader ]
%add.ptr16.phi = phi i16* [ %add.ptr16.inc, %for.body ], [ %add.ptr3, %for.body.preheader ]
%add.ptr21.phi = phi i16* [ %add.ptr21.inc, %for.body ], [ %add.ptr4, %for.body.preheader ]
%add.ptr26.phi = phi i16* [ %add.ptr26.inc, %for.body ], [ %add.ptr5, %for.body.preheader ]
%i.058.pmt = phi i32 [ %inc.pmt, %for.body ], [ 0, %for.body.preheader ]
%v.sroa.0.157 = phi i16 [ %v.sroa.0.0.extract.trunc34, %for.body ], [ %v.sroa.0.0.extract.trunc, %for.body.preheader ]
%v.sroa.4.156 = phi i16 [ %v.sroa.4.0.extract.trunc36, %for.body ], [ %v.sroa.4.0.extract.trunc, %for.body.preheader ]
%v.sroa.5.155 = phi i16 [ %v.sroa.5.0.extract.trunc38, %for.body ], [ %v.sroa.5.0.extract.trunc, %for.body.preheader ]
%v.sroa.6.154 = phi i16 [ %v.sroa.6.0.extract.trunc40, %for.body ], [ %v.sroa.6.0.extract.trunc, %for.body.preheader ]
%q64.153.pn = phi i64* [ %q64.153, %for.body ], [ %r64, %for.body.preheader ]
%q64.153 = getelementptr inbounds i64, i64* %q64.153.pn, i32 1
store i16 %v.sroa.0.157, i16* %add.ptr11.phi, align 2
store i16 %v.sroa.4.156, i16* %add.ptr16.phi, align 2
store i16 %v.sroa.5.155, i16* %add.ptr21.phi, align 2
store i16 %v.sroa.6.154, i16* %add.ptr26.phi, align 2
%tmp2 = load i64, i64* %q64.153, align 8
%v.sroa.0.0.extract.trunc34 = trunc i64 %tmp2 to i16
%v.sroa.4.0.extract.shift35 = lshr i64 %tmp2, 16
%v.sroa.4.0.extract.trunc36 = trunc i64 %v.sroa.4.0.extract.shift35 to i16
%v.sroa.5.0.extract.shift37 = lshr i64 %tmp2, 32
%v.sroa.5.0.extract.trunc38 = trunc i64 %v.sroa.5.0.extract.shift37 to i16
%v.sroa.6.0.extract.shift39 = lshr i64 %tmp2, 48
%v.sroa.6.0.extract.trunc40 = trunc i64 %v.sroa.6.0.extract.shift39 to i16
%inc.pmt = add i32 %i.058.pmt, 1
%cmp8 = icmp slt i32 %inc.pmt, %conv
%add.ptr11.inc = getelementptr i16, i16* %add.ptr11.phi, i32 4
%add.ptr16.inc = getelementptr i16, i16* %add.ptr16.phi, i32 4
%add.ptr21.inc = getelementptr i16, i16* %add.ptr21.phi, i32 4
%add.ptr26.inc = getelementptr i16, i16* %add.ptr26.phi, i32 4
br i1 %cmp8, label %for.body, label %for.end
for.end: ; preds = %for.body, %entry
ret void
}
attributes #0 = { nounwind "target-cpu"="hexagonv65" }