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279c30993a
When the formulae search space is huge, LSR uses a series of heuristic to keep pruning the search space until the number of possible solutions are within certain limit. The big hammer of the series of heuristics is NarrowSearchSpaceByPickingWinnerRegs, which picks the register which is used by the most LSRUses and deletes the other formulae which don't use the register. This is a effective way to prune the search space, but quite often not a good way to keep the best solution. We saw cases before that the heuristic pruned the best formula candidate out of search space. To relieve the problem, we introduce a new heuristic called NarrowSearchSpaceByFilterFormulaWithSameScaledReg. The basic idea is in order to reduce the search space while keeping the best formula, we want to keep as many formulae with different Scale and ScaledReg as possible. That is because the central idea of LSR is to choose a group of loop induction variables and use those induction variables to represent LSRUses. An induction variable candidate is often represented by the Scale and ScaledReg in a formula. If we have more formulae with different ScaledReg and Scale to choose, we have better opportunity to find the best solution. That is why we believe pruning search space by only keeping the best formula with the same Scale and ScaledReg should be more effective than PickingWinnerReg. And we use two criteria to choose the best formula with the same Scale and ScaledReg. The first criteria is to select the formula using less non shared registers, and the second criteria is to select the formula with less cost got from RateFormula. The patch implements the heuristic before NarrowSearchSpaceByPickingWinnerRegs, which is the last resort. Testing shows we get 1.8% and 2% on two internal benchmarks on x86. llvm nightly testsuite performance is neutral. We also tried lsr-exp-narrow and it didn't help on the two improved internal cases we saw. Differential Revision: https://reviews.llvm.org/D34583 llvm-svn: 307269
146 lines
6.6 KiB
LLVM
146 lines
6.6 KiB
LLVM
; RUN: llc -lsr-filter-same-scaled-reg=false < %s -o - -mtriple=x86_64-apple-macosx | FileCheck %s
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; Test case for the recoloring of broken hints.
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; This is tricky to have something reasonably small to kick this optimization since
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; it requires that spliting and spilling occur.
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; The bottom line is that this test case is fragile.
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; This was reduced from the make_list function from the llvm-testsuite:
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; SingleSource/Benchmarks/McGill/chomp.c
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target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
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target triple = "x86_64-apple-macosx10.9.0"
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%struct._list = type { i32*, %struct._list* }
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@ncol = external global i32, align 4
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@nrow = external global i32, align 4
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declare noalias i32* @copy_data()
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declare noalias i8* @malloc(i64)
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declare i32 @get_value()
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declare i32 @in_wanted(i32* nocapture readonly)
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declare noalias i32* @make_data()
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; CHECK-LABEL: make_list:
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; Function prologue.
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; CHECK: pushq
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; CHECK: subq ${{[0-9]+}}, %rsp
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; Move the first argument (%data) into a temporary register.
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; It will not survive the call to malloc otherwise.
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; CHECK: movq %rdi, [[ARG1:%r[0-9a-z]+]]
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; CHECK: callq _malloc
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; Compute %data - 1 as used for load in land.rhs.i (via the variable %indvars.iv.next.i).
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; CHECK: addq $-4, [[ARG1]]
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; We use to produce a useless copy here and move %data in another temporary register.
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; CHECK-NOT: movq [[ARG1]]
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; End of the first basic block.
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; CHECK: .p2align
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; Now check that %data is used in an address computation.
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; CHECK: leaq ([[ARG1]]
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define %struct._list* @make_list(i32* nocapture readonly %data, i32* nocapture %value, i32* nocapture %all) {
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entry:
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%call = tail call i8* @malloc(i64 16)
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%next = getelementptr inbounds i8, i8* %call, i64 8
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%tmp = bitcast i8* %next to %struct._list**
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%tmp2 = bitcast i8* %call to %struct._list*
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%.pre78 = load i32, i32* @ncol, align 4
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br label %for.cond1.preheader
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for.cond1.preheader: ; preds = %for.inc32, %entry
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%tmp4 = phi i32 [ %.pre78, %entry ], [ 0, %for.inc32 ]
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%current.077 = phi %struct._list* [ %tmp2, %entry ], [ %current.1.lcssa, %for.inc32 ]
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%cmp270 = icmp eq i32 %tmp4, 0
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br i1 %cmp270, label %for.inc32, label %for.body3
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for.body3: ; preds = %if.end31, %for.cond1.preheader
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%current.173 = phi %struct._list* [ %current.2, %if.end31 ], [ %current.077, %for.cond1.preheader ]
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%row.172 = phi i32 [ %row.3, %if.end31 ], [ 0, %for.cond1.preheader ]
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%col.071 = phi i32 [ %inc, %if.end31 ], [ 0, %for.cond1.preheader ]
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%call4 = tail call i32* @make_data()
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%tmp5 = load i32, i32* @ncol, align 4
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%tobool14.i = icmp eq i32 %tmp5, 0
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br i1 %tobool14.i, label %while.cond.i, label %while.body.lr.ph.i
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while.body.lr.ph.i: ; preds = %for.body3
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%tmp6 = sext i32 %tmp5 to i64
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br label %while.body.i
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while.body.i: ; preds = %while.body.i, %while.body.lr.ph.i
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%indvars.iv.i = phi i64 [ %tmp6, %while.body.lr.ph.i ], [ %indvars.iv.next.i, %while.body.i ]
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%indvars.iv.next.i = add nsw i64 %indvars.iv.i, -1
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%tmp9 = trunc i64 %indvars.iv.next.i to i32
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%tobool.i = icmp eq i32 %tmp9, 0
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br i1 %tobool.i, label %while.cond.i, label %while.body.i
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while.cond.i: ; preds = %land.rhs.i, %while.body.i, %for.body3
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%indvars.iv.i64 = phi i64 [ %indvars.iv.next.i65, %land.rhs.i ], [ 0, %for.body3 ], [ %tmp6, %while.body.i ]
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%indvars.iv.next.i65 = add nsw i64 %indvars.iv.i64, -1
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%tmp10 = trunc i64 %indvars.iv.i64 to i32
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%tobool.i66 = icmp eq i32 %tmp10, 0
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br i1 %tobool.i66, label %if.else, label %land.rhs.i
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land.rhs.i: ; preds = %while.cond.i
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%arrayidx.i67 = getelementptr inbounds i32, i32* %call4, i64 %indvars.iv.next.i65
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%tmp11 = load i32, i32* %arrayidx.i67, align 4
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%arrayidx2.i68 = getelementptr inbounds i32, i32* %data, i64 %indvars.iv.next.i65
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%tmp12 = load i32, i32* %arrayidx2.i68, align 4
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%cmp.i69 = icmp eq i32 %tmp11, %tmp12
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br i1 %cmp.i69, label %while.cond.i, label %equal_data.exit
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equal_data.exit: ; preds = %land.rhs.i
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%cmp3.i = icmp slt i32 %tmp10, 1
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br i1 %cmp3.i, label %if.else, label %if.then
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if.then: ; preds = %equal_data.exit
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%next7 = getelementptr inbounds %struct._list, %struct._list* %current.173, i64 0, i32 1
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%tmp14 = load %struct._list*, %struct._list** %next7, align 8
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%next12 = getelementptr inbounds %struct._list, %struct._list* %tmp14, i64 0, i32 1
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store %struct._list* null, %struct._list** %next12, align 8
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%tmp15 = load %struct._list*, %struct._list** %next7, align 8
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%tmp16 = load i32, i32* %value, align 4
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%cmp14 = icmp eq i32 %tmp16, 1
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%.tmp16 = select i1 %cmp14, i32 0, i32 %tmp16
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%tmp18 = load i32, i32* %all, align 4
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%tmp19 = or i32 %tmp18, %.tmp16
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%tmp20 = icmp eq i32 %tmp19, 0
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br i1 %tmp20, label %if.then19, label %if.end31
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if.then19: ; preds = %if.then
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%call21 = tail call i32 @in_wanted(i32* %call4)
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br label %if.end31
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if.else: ; preds = %equal_data.exit, %while.cond.i
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%cmp26 = icmp eq i32 %col.071, 0
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%.row.172 = select i1 %cmp26, i32 0, i32 %row.172
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%sub30 = add nsw i32 %tmp5, -1
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br label %if.end31
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if.end31: ; preds = %if.else, %if.then19, %if.then
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%col.1 = phi i32 [ %sub30, %if.else ], [ 0, %if.then ], [ 0, %if.then19 ]
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%row.3 = phi i32 [ %.row.172, %if.else ], [ %row.172, %if.then ], [ 0, %if.then19 ]
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%current.2 = phi %struct._list* [ %current.173, %if.else ], [ %tmp15, %if.then ], [ %tmp15, %if.then19 ]
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%inc = add nsw i32 %col.1, 1
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%tmp25 = load i32, i32* @ncol, align 4
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%cmp2 = icmp eq i32 %inc, %tmp25
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br i1 %cmp2, label %for.cond1.for.inc32_crit_edge, label %for.body3
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for.cond1.for.inc32_crit_edge: ; preds = %if.end31
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%.pre79 = load i32, i32* @nrow, align 4
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br label %for.inc32
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for.inc32: ; preds = %for.cond1.for.inc32_crit_edge, %for.cond1.preheader
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%tmp26 = phi i32 [ %.pre79, %for.cond1.for.inc32_crit_edge ], [ 0, %for.cond1.preheader ]
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%current.1.lcssa = phi %struct._list* [ %current.2, %for.cond1.for.inc32_crit_edge ], [ %current.077, %for.cond1.preheader ]
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%row.1.lcssa = phi i32 [ %row.3, %for.cond1.for.inc32_crit_edge ], [ 0, %for.cond1.preheader ]
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%inc33 = add nsw i32 %row.1.lcssa, 1
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%cmp = icmp eq i32 %inc33, %tmp26
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br i1 %cmp, label %for.end34, label %for.cond1.preheader
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for.end34: ; preds = %for.inc32
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%.pre = load %struct._list*, %struct._list** %tmp, align 8
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ret %struct._list* %.pre
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}
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