[llvm] r340871 - [SimpleLoopUnswitch] Form dedicated exits after trivial unswitches.
Alina Sbirlea via llvm-commits
llvm-commits at lists.llvm.org
Tue Aug 28 13:41:05 PDT 2018
Author: asbirlea
Date: Tue Aug 28 13:41:05 2018
New Revision: 340871
URL: http://llvm.org/viewvc/llvm-project?rev=340871&view=rev
Log:
[SimpleLoopUnswitch] Form dedicated exits after trivial unswitches.
Summary:
Form dedicated exits after trivial unswitches.
Fixes PR38737, PR38283.
Reviewers: chandlerc, fedor.sergeev
Subscribers: sanjoy, jlebar, uabelho, llvm-commits
Differential Revision: https://reviews.llvm.org/D51375
Added:
llvm/trunk/test/Transforms/SimpleLoopUnswitch/formDedicatedAfterTrivial1.ll
llvm/trunk/test/Transforms/SimpleLoopUnswitch/formDedicatedAfterTrivial2.ll
llvm/trunk/test/Transforms/SimpleLoopUnswitch/formDedicatedAfterTrivial3.ll
Modified:
llvm/trunk/lib/Transforms/Scalar/SimpleLoopUnswitch.cpp
Modified: llvm/trunk/lib/Transforms/Scalar/SimpleLoopUnswitch.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/SimpleLoopUnswitch.cpp?rev=340871&r1=340870&r2=340871&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/SimpleLoopUnswitch.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/SimpleLoopUnswitch.cpp Tue Aug 28 13:41:05 2018
@@ -302,10 +302,11 @@ static void hoistLoopToNewParent(Loop &L
formLCSSA(*OldContainingL, DT, &LI, nullptr);
// We shouldn't need to form dedicated exits because the exit introduced
- // here is the (just split by unswitching) preheader. As such, it is
- // necessarily dedicated.
- assert(OldContainingL->hasDedicatedExits() &&
- "Unexpected predecessor of hoisted loop preheader!");
+ // here is the (just split by unswitching) preheader. However, after trivial
+ // unswitching it is possible to get new non-dedicated exits out of parent
+ // loop so let's conservatively form dedicated exit blocks and figure out
+ // if we can optimize later.
+ formDedicatedExitBlocks(OldContainingL, &DT, &LI, /*PreserveLCSSA*/ true);
}
}
@@ -482,6 +483,7 @@ static bool unswitchTrivialBranch(Loop &
if (FullUnswitch)
hoistLoopToNewParent(L, *NewPH, DT, LI);
+ LLVM_DEBUG(dbgs() << " done: unswitching trivial branch...\n");
++NumTrivial;
++NumBranches;
return true;
@@ -539,7 +541,7 @@ static bool unswitchTrivialSwitch(Loop &
else if (ExitCaseIndices.empty())
return false;
- LLVM_DEBUG(dbgs() << " unswitching trivial cases...\n");
+ LLVM_DEBUG(dbgs() << " unswitching trivial switch...\n");
// We may need to invalidate SCEVs for the outermost loop reached by any of
// the exits.
@@ -739,6 +741,7 @@ static bool unswitchTrivialSwitch(Loop &
++NumTrivial;
++NumSwitches;
+ LLVM_DEBUG(dbgs() << " done: unswitching trivial switch...\n");
return true;
}
Added: llvm/trunk/test/Transforms/SimpleLoopUnswitch/formDedicatedAfterTrivial1.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/SimpleLoopUnswitch/formDedicatedAfterTrivial1.ll?rev=340871&view=auto
==============================================================================
--- llvm/trunk/test/Transforms/SimpleLoopUnswitch/formDedicatedAfterTrivial1.ll (added)
+++ llvm/trunk/test/Transforms/SimpleLoopUnswitch/formDedicatedAfterTrivial1.ll Tue Aug 28 13:41:05 2018
@@ -0,0 +1,25 @@
+; RUN: opt < %s -simple-loop-unswitch -disable-output
+
+; PR38283
+; PR38737
+define void @f1() {
+for.cond1thread-pre-split.lr.ph.lr.ph:
+ %tobool4 = icmp eq i16 undef, 0
+ br label %for.cond1thread-pre-split
+
+for.cond1thread-pre-split: ; preds = %if.end, %for.cond1thread-pre-split.lr.ph.lr.ph
+ %tobool3 = icmp eq i16 undef, 0
+ br label %for.body2
+
+for.body2: ; preds = %if.end6, %for.cond1thread-pre-split
+ br i1 %tobool3, label %if.end, label %for.end
+
+if.end: ; preds = %for.body2
+ br i1 %tobool4, label %if.end6, label %for.cond1thread-pre-split
+
+if.end6: ; preds = %if.end
+ br i1 undef, label %for.body2, label %for.end
+
+for.end: ; preds = %if.end6, %for.body2
+ ret void
+}
Added: llvm/trunk/test/Transforms/SimpleLoopUnswitch/formDedicatedAfterTrivial2.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/SimpleLoopUnswitch/formDedicatedAfterTrivial2.ll?rev=340871&view=auto
==============================================================================
--- llvm/trunk/test/Transforms/SimpleLoopUnswitch/formDedicatedAfterTrivial2.ll (added)
+++ llvm/trunk/test/Transforms/SimpleLoopUnswitch/formDedicatedAfterTrivial2.ll Tue Aug 28 13:41:05 2018
@@ -0,0 +1,22 @@
+; RUN: opt < %s -simple-loop-unswitch -disable-output
+
+; PR38283
+; PR38737
+define void @Test(i32) {
+entry:
+ %trunc = trunc i32 %0 to i3
+ br label %outer
+outer:
+ br label %inner
+inner:
+ switch i3 %trunc, label %crit_edge [
+ i3 2, label %break
+ i3 1, label %loopexit
+ ]
+crit_edge:
+ br i1 true, label %loopexit, label %inner
+loopexit:
+ ret void
+break:
+ br label %outer
+}
Added: llvm/trunk/test/Transforms/SimpleLoopUnswitch/formDedicatedAfterTrivial3.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/SimpleLoopUnswitch/formDedicatedAfterTrivial3.ll?rev=340871&view=auto
==============================================================================
--- llvm/trunk/test/Transforms/SimpleLoopUnswitch/formDedicatedAfterTrivial3.ll (added)
+++ llvm/trunk/test/Transforms/SimpleLoopUnswitch/formDedicatedAfterTrivial3.ll Tue Aug 28 13:41:05 2018
@@ -0,0 +1,37 @@
+; RUN: opt < %s -simple-loop-unswitch -disable-output
+
+; PR38283
+; PR38737
+declare void @func_1()
+
+define void @func_9(i32 signext %arg) {
+bb:
+ br label %bb5
+bb5: ; preds = %bb24, %bb
+ %tmp3.0 = phi i32 [ undef, %bb ], [ %tmp29, %bb24 ]
+ %tmp11 = icmp eq i32 %arg, 0
+ %tmp15 = icmp eq i32 %tmp3.0, 0
+ %spec.select = select i1 %tmp15, i32 0, i32 49
+ %tmp1.2 = select i1 %tmp11, i32 %spec.select, i32 9
+ %trunc = trunc i32 %tmp1.2 to i6
+ br label %bb9
+
+bb9: ; preds = %bb5, %bb19
+ %tmp2.03 = phi i32 [ 0, %bb5 ], [ %tmp21, %bb19 ]
+ switch i6 %trunc, label %bb24 [
+ i6 0, label %bb19
+ i6 -15, label %bb22
+ ]
+
+bb19: ; preds = %bb9
+ %tmp21 = add nuw nsw i32 %tmp2.03, 1
+ %tmp8 = icmp eq i32 %tmp21, 25
+ br i1 %tmp8, label %bb22, label %bb9
+
+bb22: ; preds = %bb19, %bb9
+ unreachable
+
+bb24: ; preds = %bb9
+ %tmp29 = or i32 %tmp3.0, 1
+ br label %bb5
+}
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