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2be00d9e54
Current tail duplication integrated in bb layout is designed to increase the fallthrough from a BB's predecessor to its successor, but we have observed cases that duplication doesn't increase fallthrough, or it brings too much size overhead. To overcome these two issues in function canTailDuplicateUnplacedPreds I add two checks: make sure there is at least one duplication in current work set. the number of duplication should not exceed the number of successors. The modification in hasBetterLayoutPredecessor fixes a bug that potential predecessor must be at the bottom of a chain. Differential Revision: https://reviews.llvm.org/D64376
82 lines
3.5 KiB
LLVM
82 lines
3.5 KiB
LLVM
; RUN: llc -verify-machineinstrs < %s | FileCheck %s
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target datalayout = "E-p:32:32"
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target triple = "powerpc-unknown-linux-gnu"
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;CHECK-LABEL: foo:
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; There are 4 inner loops (%bb, %bb12, %bb25, %bb38) that all exit to %cond_next48
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; The last (whichever it is) should have a fallthrough exit, and the other three
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; need an unconditional branch. No other block should have an unconditional
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; branch to cond_next48
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;CHECK: .LBB0_7: # %cond_next48
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;CHECK: b .LBB0_7
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;CHECK: b .LBB0_7
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;CHECK: b .LBB0_7
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define void @foo(i32 %W, i32 %X, i32 %Y, i32 %Z) {
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entry:
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%tmp1 = and i32 %W, 1 ; <i32> [#uses=1]
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%tmp1.upgrd.1 = icmp eq i32 %tmp1, 0 ; <i1> [#uses=1]
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br i1 %tmp1.upgrd.1, label %cond_false, label %bb5
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bb: ; preds = %bb5, %bb
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%indvar77 = phi i32 [ %indvar.next78, %bb ], [ 0, %bb5 ] ; <i32> [#uses=1]
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%tmp2 = tail call i32 (...) @bar( ) ; <i32> [#uses=0]
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%indvar.next78 = add i32 %indvar77, 1 ; <i32> [#uses=2]
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%exitcond79 = icmp eq i32 %indvar.next78, %X ; <i1> [#uses=1]
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br i1 %exitcond79, label %cond_next48, label %bb
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bb5: ; preds = %entry
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%tmp = icmp eq i32 %X, 0 ; <i1> [#uses=1]
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br i1 %tmp, label %cond_next48, label %bb
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cond_false: ; preds = %entry
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%tmp10 = and i32 %W, 2 ; <i32> [#uses=1]
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%tmp10.upgrd.2 = icmp eq i32 %tmp10, 0 ; <i1> [#uses=1]
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br i1 %tmp10.upgrd.2, label %cond_false20, label %bb16
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bb12: ; preds = %bb16, %bb12
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%indvar72 = phi i32 [ %indvar.next73, %bb12 ], [ 0, %bb16 ] ; <i32> [#uses=1]
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%tmp13 = tail call i32 (...) @bar( ) ; <i32> [#uses=0]
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%indvar.next73 = add i32 %indvar72, 1 ; <i32> [#uses=2]
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%exitcond74 = icmp eq i32 %indvar.next73, %Y ; <i1> [#uses=1]
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br i1 %exitcond74, label %cond_next48, label %bb12
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bb16: ; preds = %cond_false
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%tmp18 = icmp eq i32 %Y, 0 ; <i1> [#uses=1]
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br i1 %tmp18, label %cond_next48, label %bb12
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cond_false20: ; preds = %cond_false
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%tmp23 = and i32 %W, 4 ; <i32> [#uses=1]
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%tmp23.upgrd.3 = icmp eq i32 %tmp23, 0 ; <i1> [#uses=1]
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br i1 %tmp23.upgrd.3, label %cond_false33, label %bb29
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bb25: ; preds = %bb29, %bb25
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%indvar67 = phi i32 [ %indvar.next68, %bb25 ], [ 0, %bb29 ] ; <i32> [#uses=1]
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%tmp26 = tail call i32 (...) @bar( ) ; <i32> [#uses=0]
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%indvar.next68 = add i32 %indvar67, 1 ; <i32> [#uses=2]
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%exitcond69 = icmp eq i32 %indvar.next68, %Z ; <i1> [#uses=1]
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br i1 %exitcond69, label %cond_next48, label %bb25
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bb29: ; preds = %cond_false20
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%tmp31 = icmp eq i32 %Z, 0 ; <i1> [#uses=1]
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br i1 %tmp31, label %cond_next48, label %bb25
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cond_false33: ; preds = %cond_false20
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%tmp36 = and i32 %W, 8 ; <i32> [#uses=1]
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%tmp36.upgrd.4 = icmp eq i32 %tmp36, 0 ; <i1> [#uses=1]
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br i1 %tmp36.upgrd.4, label %cond_next48, label %bb42
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bb38: ; preds = %bb42
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%tmp39 = tail call i32 (...) @bar( ) ; <i32> [#uses=0]
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%indvar.next = add i32 %indvar, 1 ; <i32> [#uses=1]
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br label %bb42
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bb42: ; preds = %bb38, %cond_false33
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%indvar = phi i32 [ %indvar.next, %bb38 ], [ 0, %cond_false33 ] ; <i32> [#uses=4]
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%W_addr.0 = sub i32 %W, %indvar ; <i32> [#uses=1]
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%exitcond = icmp eq i32 %indvar, %W ; <i1> [#uses=1]
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br i1 %exitcond, label %cond_next48, label %bb38
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cond_next48: ; preds = %bb42, %cond_false33, %bb29, %bb25, %bb16, %bb12, %bb5, %bb
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%W_addr.1 = phi i32 [ %W, %bb5 ], [ %W, %bb16 ], [ %W, %bb29 ], [ %W, %cond_false33 ], [ %W_addr.0, %bb42 ], [ %W, %bb25 ], [ %W, %bb12 ], [ %W, %bb ] ; <i32> [#uses=1]
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%tmp50 = icmp eq i32 %W_addr.1, 0 ; <i1> [#uses=1]
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br i1 %tmp50, label %UnifiedReturnBlock, label %cond_true51
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cond_true51: ; preds = %cond_next48
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%tmp52 = tail call i32 (...) @bar( ) ; <i32> [#uses=0]
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ret void
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UnifiedReturnBlock: ; preds = %cond_next48
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ret void
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}
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declare i32 @bar(...)
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