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llvm-project/llvm/test/Transforms/LICM/sink.ll

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Add Loop Sink pass to reverse the LICM based of basic block frequency. Summary: LICM may hoist instructions to preheader speculatively. Before code generation, we need to sink down the hoisted instructions inside to loop if it's beneficial. This pass is a reverse of LICM: looking at instructions in preheader and sinks the instruction to basic blocks inside the loop body if basic block frequency is smaller than the preheader frequency. Reviewers: hfinkel, davidxl, chandlerc Subscribers: anna, modocache, mgorny, beanz, reames, dberlin, chandlerc, mcrosier, junbuml, sanjoy, mzolotukhin, llvm-commits Differential Revision: https://reviews.llvm.org/D22778 llvm-svn: 285308
2016-10-28 00:30:08 +08:00
; RUN: opt -S -licm < %s | FileCheck %s --check-prefix=CHECK-LICM
; RUN: opt -S -licm < %s | opt -S -loop-sink | FileCheck %s --check-prefix=CHECK-SINK
[PM] Port LoopSink to the new pass manager. Like several other loop passes (the vectorizer, etc) this pass doesn't really fit the model of a loop pass. The critical distinction is that it isn't intended to be pipelined together with other loop passes. I plan to add some documentation to the loop pass manager to make this more clear on that side. LoopSink is also different because it doesn't really need a lot of the infrastructure of our loop passes. For example, if there aren't loop invariant instructions causing a preheader to exist, there is no need to form a preheader. It also doesn't need LCSSA because this pass is only involved in sinking invariant instructions from a preheader into the loop, not reasoning about live-outs. This allows some nice simplifications to the pass in the new PM where we can directly walk the loops once without restructuring them. Differential Revision: https://reviews.llvm.org/D28921 llvm-svn: 292589
2017-01-20 16:42:19 +08:00
; RUN: opt -S < %s -passes='require<opt-remark-emit>,loop(licm),loop-sink' \
; RUN: | FileCheck %s --check-prefix=CHECK-SINK
Add Loop Sink pass to reverse the LICM based of basic block frequency. Summary: LICM may hoist instructions to preheader speculatively. Before code generation, we need to sink down the hoisted instructions inside to loop if it's beneficial. This pass is a reverse of LICM: looking at instructions in preheader and sinks the instruction to basic blocks inside the loop body if basic block frequency is smaller than the preheader frequency. Reviewers: hfinkel, davidxl, chandlerc Subscribers: anna, modocache, mgorny, beanz, reames, dberlin, chandlerc, mcrosier, junbuml, sanjoy, mzolotukhin, llvm-commits Differential Revision: https://reviews.llvm.org/D22778 llvm-svn: 285308
2016-10-28 00:30:08 +08:00
; Original source code:
; int g;
; int foo(int p, int x) {
; for (int i = 0; i != x; i++)
; if (__builtin_expect(i == p, 0)) {
; x += g; x *= g;
; }
; return x;
; }
;
; Load of global value g should not be hoisted to preheader.
@g = global i32 0, align 4
Enable Loop Sink pass for functions that has profile. Summary: For functions with profile data, we are confident that loop sink will be optimal in sinking code. Reviewers: davidxl, hfinkel Subscribers: mehdi_amini, mzolotukhin, llvm-commits Differential Revision: https://reviews.llvm.org/D26155 llvm-svn: 286325
2016-11-09 08:58:19 +08:00
define i32 @foo(i32, i32) #0 !prof !2 {
Add Loop Sink pass to reverse the LICM based of basic block frequency. Summary: LICM may hoist instructions to preheader speculatively. Before code generation, we need to sink down the hoisted instructions inside to loop if it's beneficial. This pass is a reverse of LICM: looking at instructions in preheader and sinks the instruction to basic blocks inside the loop body if basic block frequency is smaller than the preheader frequency. Reviewers: hfinkel, davidxl, chandlerc Subscribers: anna, modocache, mgorny, beanz, reames, dberlin, chandlerc, mcrosier, junbuml, sanjoy, mzolotukhin, llvm-commits Differential Revision: https://reviews.llvm.org/D22778 llvm-svn: 285308
2016-10-28 00:30:08 +08:00
%3 = icmp eq i32 %1, 0
br i1 %3, label %._crit_edge, label %.lr.ph.preheader
.lr.ph.preheader:
br label %.lr.ph
; CHECK-LICM: .lr.ph.preheader:
; CHECK-LICM: load i32, i32* @g
; CHECK-LICM: br label %.lr.ph
.lr.ph:
%.03 = phi i32 [ %8, %.combine ], [ 0, %.lr.ph.preheader ]
%.012 = phi i32 [ %.1, %.combine ], [ %1, %.lr.ph.preheader ]
%4 = icmp eq i32 %.03, %0
br i1 %4, label %.then, label %.combine, !prof !1
.then:
%5 = load i32, i32* @g, align 4
%6 = add nsw i32 %5, %.012
%7 = mul nsw i32 %6, %5
br label %.combine
; CHECK-SINK: .then:
; CHECK-SINK: load i32, i32* @g
; CHECK-SINK: br label %.combine
.combine:
%.1 = phi i32 [ %7, %.then ], [ %.012, %.lr.ph ]
%8 = add nuw nsw i32 %.03, 1
%9 = icmp eq i32 %8, %.1
br i1 %9, label %._crit_edge.loopexit, label %.lr.ph
._crit_edge.loopexit:
%.1.lcssa = phi i32 [ %.1, %.combine ]
br label %._crit_edge
._crit_edge:
%.01.lcssa = phi i32 [ 0, %2 ], [ %.1.lcssa, %._crit_edge.loopexit ]
ret i32 %.01.lcssa
}
!1 = !{!"branch_weights", i32 1, i32 2000}
Enable Loop Sink pass for functions that has profile. Summary: For functions with profile data, we are confident that loop sink will be optimal in sinking code. Reviewers: davidxl, hfinkel Subscribers: mehdi_amini, mzolotukhin, llvm-commits Differential Revision: https://reviews.llvm.org/D26155 llvm-svn: 286325
2016-11-09 08:58:19 +08:00
!2 = !{!"function_entry_count", i64 1}