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[HotColdSplit] Allow outlining with live outputs 

Prior to r348205, extracting code regions with live output values was
disabled because of a miscompilation (PR39433). Lift the restriction as
PR39433 has been addressed.

Tested on LNT+externals, on a run of check-llvm in a stage2 build, and
with a full build of iOS (with hot/cold splitting enabled).

As a drive-by, remove an errant TODO.

llvm-svn: 351492
This commit is contained in:
Vedant Kumar 2019-01-17 22:36:05 +00:00
parent b70e20db62
commit f529b50702
2 changed files with 68 additions and 10 deletions
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10
llvm/lib/Transforms/IPO/HotColdSplitting.cpp
View File

@ -252,16 +252,6 @@ Function *HotColdSplitting::extractColdRegion(const BlockSequence &Region,
/* AllowAlloca */ false,
/* Suffix */ "cold." + std::to_string(Count));
SetVector<Value *> Inputs, Outputs, Sinks;
CE.findInputsOutputs(Inputs, Outputs, Sinks);
// Do not extract regions that have live exit variables.
if (Outputs.size() > 0) {
LLVM_DEBUG(llvm::dbgs() << "Not outlining; live outputs\n");
return nullptr;
}
// TODO: Run MergeBasicBlockIntoOnlyPred on the outlined function.
Function *OrigF = Region[0]->getParent();
if (Function *OutF = CE.extractCodeRegion()) {
User *U = *OutF->user_begin();

68
llvm/test/Transforms/HotColdSplit/split-phis-in-exit-blocks.ll Normal file
View File

@ -0,0 +1,68 @@
; RUN: opt -hotcoldsplit-threshold=0 -hotcoldsplit -S < %s | FileCheck %s
target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-apple-macosx10.14.0"
; CHECK-LABEL: define {{.*}}@pluto(
; CHECK-NEXT: bb:
; CHECK-NEXT: %tmp8.ce.loc = alloca i1
; CHECK-NEXT: switch i8 undef, label %codeRepl [
; CHECK-NEXT: i8 0, label %bb7
; CHECK-NEXT: i8 1, label %bb7
; CHECK-NEXT: ]
;
; CHECK: codeRepl:
; CHECK-NEXT: call void @pluto.cold.1(i1* %tmp8.ce.loc)
; CHECK-NEXT: %tmp8.ce.reload = load i1, i1* %tmp8.ce.loc
; CHECK-NEXT: br label %bb7
;
; CHECK: bb7:
; CHECK: %tmp8 = phi i1 [ true, %bb ], [ true, %bb ], [ %tmp8.ce.reload, %codeRepl ]
; CHECK: ret void
; CHECK-LABEL: define {{.*}}@pluto.cold.1(
; CHECK: call {{.*}}@sideeffect(i32 1)
; CHECK: call {{.*}}@sink(
; CHECK: call {{.*}}@sideeffect(i32 3)
; CHECK: call {{.*}}@sideeffect(i32 4)
; CHECK: call {{.*}}@sideeffect(i32 5)
define void @pluto() {
bb:
switch i8 undef, label %bb1 [
i8 0, label %bb7
i8 1, label %bb7
]
bb1: ; preds = %bb
call void @sideeffect(i32 1)
br label %bb2
bb2: ; preds = %bb1
call void @sink()
br i1 undef, label %bb7, label %bb3
bb3: ; preds = %bb2
call void @sideeffect(i32 3)
br label %bb4
bb4: ; preds = %bb3
call void @sideeffect(i32 4)
br i1 undef, label %bb5, label %bb6
bb5: ; preds = %bb4
call void @sideeffect(i32 5)
br label %bb6
bb6: ; preds = %bb5, %bb4
%tmp = phi i1 [ true, %bb5 ], [ false, %bb4 ]
call void @sideeffect(i32 6)
br label %bb7
bb7: ; preds = %bb6, %bb2, %bb, %bb
%tmp8 = phi i1 [ true, %bb ], [ true, %bb ], [ true, %bb2 ], [ %tmp, %bb6 ]
ret void
}
declare void @sink() cold
declare void @sideeffect(i32)