[llvm] 233659c - [LoopFlatten] Enable it by default
Sjoerd Meijer via llvm-commits
llvm-commits at lists.llvm.org
Mon Oct 17 04:42:50 PDT 2022
Author: Sjoerd Meijer
Date: 2022-10-17T17:11:39+05:30
New Revision: 233659c7ae9b83b64a9f739d340736bca39c3d2e
URL: https://github.com/llvm/llvm-project/commit/233659c7ae9b83b64a9f739d340736bca39c3d2e
DIFF: https://github.com/llvm/llvm-project/commit/233659c7ae9b83b64a9f739d340736bca39c3d2e.diff
LOG: [LoopFlatten] Enable it by default
LoopFlatten has been in the code base off by default for years, but this
enables it to run by default. Downstream this has been running for
years, so it has been exposed to quite some code. Then around the time
we switched to the NPM, several fixes went in related to updating the
MemorySSA state and we moved it to a loop pass manager, which both
helped preventing rerunning certain analysis passes, and thus helped a
bit with compile-times.
About compile-times, adding a pass isn't free, but this should see only
very minor increases. The pass is relatively simple and there shouldn't
be anything algorithmically expensive because all it does is looking at
inner/outer loops and it checks assumptions on loop increments and
indices. If we see increases, I expect this to mainly come from
invalidation of analysis info, and perhaps subsequent passes to trigger
and do more. Despite its simplicity/restrictions, it triggers in most
code-bases, which makes it worth to enable this by default.
Differential Revision: https://reviews.llvm.org/D109958
Added:
Modified:
llvm/docs/ReleaseNotes.rst
llvm/lib/Transforms/IPO/PassManagerBuilder.cpp
llvm/lib/Transforms/Scalar/LoopFlatten.cpp
llvm/test/Other/new-pm-defaults.ll
llvm/test/Other/new-pm-lto-defaults.ll
llvm/test/Other/new-pm-thinlto-defaults.ll
llvm/test/Other/new-pm-thinlto-postlink-pgo-defaults.ll
llvm/test/Other/new-pm-thinlto-postlink-samplepgo-defaults.ll
llvm/test/Other/new-pm-thinlto-prelink-pgo-defaults.ll
llvm/test/Other/new-pm-thinlto-prelink-samplepgo-defaults.ll
Removed:
################################################################################
diff --git a/llvm/docs/ReleaseNotes.rst b/llvm/docs/ReleaseNotes.rst
index 6b4711ff061ec..1c1d5d5736cd4 100644
--- a/llvm/docs/ReleaseNotes.rst
+++ b/llvm/docs/ReleaseNotes.rst
@@ -12,6 +12,7 @@ LLVM |release| Release Notes
Release notes for previous releases can be found on
`the Download Page <https://releases.llvm.org/download.html>`_.
+* The LoopFlatten pass is now enabled by default.
Introduction
============
diff --git a/llvm/lib/Transforms/IPO/PassManagerBuilder.cpp b/llvm/lib/Transforms/IPO/PassManagerBuilder.cpp
index 52e4fa4011837..0c41db1db5f7f 100644
--- a/llvm/lib/Transforms/IPO/PassManagerBuilder.cpp
+++ b/llvm/lib/Transforms/IPO/PassManagerBuilder.cpp
@@ -83,7 +83,7 @@ cl::opt<bool> EnableUnrollAndJam("enable-unroll-and-jam", cl::init(false),
cl::Hidden,
cl::desc("Enable Unroll And Jam Pass"));
-cl::opt<bool> EnableLoopFlatten("enable-loop-flatten", cl::init(false),
+cl::opt<bool> EnableLoopFlatten("enable-loop-flatten", cl::init(true),
cl::Hidden,
cl::desc("Enable the LoopFlatten Pass"));
diff --git a/llvm/lib/Transforms/Scalar/LoopFlatten.cpp b/llvm/lib/Transforms/Scalar/LoopFlatten.cpp
index c530e77c844f8..944b449a24ec8 100644
--- a/llvm/lib/Transforms/Scalar/LoopFlatten.cpp
+++ b/llvm/lib/Transforms/Scalar/LoopFlatten.cpp
@@ -762,6 +762,7 @@ static bool DoFlattenLoopPair(FlattenInfo &FI, DominatorTree *DT, LoopInfo *LI,
// deleted, and any information that have about the outer loop invalidated.
SE->forgetLoop(FI.OuterLoop);
SE->forgetLoop(FI.InnerLoop);
+ SE->forgetLoopDispositions();
if (U)
U->markLoopAsDeleted(*FI.InnerLoop, FI.InnerLoop->getName());
LI->erase(FI.InnerLoop);
diff --git a/llvm/test/Other/new-pm-defaults.ll b/llvm/test/Other/new-pm-defaults.ll
index 162663a0aa969..2b57c04e3dc32 100644
--- a/llvm/test/Other/new-pm-defaults.ll
+++ b/llvm/test/Other/new-pm-defaults.ll
@@ -174,6 +174,7 @@
; CHECK-O-NEXT: Running pass: LICM
; CHECK-O-NEXT: Running pass: SimpleLoopUnswitchPass
; CHECK-O-NEXT: Running analysis: OuterAnalysisManagerProxy
+; CHECK-O-NEXT: Running pass: LoopFlattenPass
; CHECK-O-NEXT: Running pass: SimplifyCFGPass
; CHECK-O-NEXT: Running pass: InstCombinePass
; CHECK-O-NEXT: Running pass: LoopSimplifyPass
diff --git a/llvm/test/Other/new-pm-lto-defaults.ll b/llvm/test/Other/new-pm-lto-defaults.ll
index 6432d806ad9c1..aa772c13f21a5 100644
--- a/llvm/test/Other/new-pm-lto-defaults.ll
+++ b/llvm/test/Other/new-pm-lto-defaults.ll
@@ -116,6 +116,7 @@
; CHECK-O23SZ-NEXT: Running pass: MergedLoadStoreMotionPass on foo
; CHECK-O23SZ-NEXT: Running pass: LoopSimplifyPass on foo
; CHECK-O23SZ-NEXT: Running pass: LCSSAPass on foo
+; CHECK-O23SZ-NEXT: Running pass: LoopFlattenPass on loop
; CHECK-O23SZ-NEXT: Running pass: IndVarSimplifyPass on loop
; CHECK-O23SZ-NEXT: Running pass: LoopDeletionPass on loop
; CHECK-O23SZ-NEXT: Running pass: LoopFullUnrollPass on loop
diff --git a/llvm/test/Other/new-pm-thinlto-defaults.ll b/llvm/test/Other/new-pm-thinlto-defaults.ll
index 7ef6ac1d5f944..811047b0ebb86 100644
--- a/llvm/test/Other/new-pm-thinlto-defaults.ll
+++ b/llvm/test/Other/new-pm-thinlto-defaults.ll
@@ -149,6 +149,7 @@
; CHECK-O-NEXT: Running pass: LICM
; CHECK-O-NEXT: Running pass: SimpleLoopUnswitchPass
; CHECK-O-NEXT: Running analysis: OuterAnalysisManagerProxy
+; CHECK-O-NEXT: Running pass: LoopFlattenPass
; CHECK-O-NEXT: Running pass: SimplifyCFGPass
; CHECK-O-NEXT: Running pass: InstCombinePass
; CHECK-O-NEXT: Running pass: LoopSimplifyPass
diff --git a/llvm/test/Other/new-pm-thinlto-postlink-pgo-defaults.ll b/llvm/test/Other/new-pm-thinlto-postlink-pgo-defaults.ll
index 524e671c01ac7..b9933d5977f08 100644
--- a/llvm/test/Other/new-pm-thinlto-postlink-pgo-defaults.ll
+++ b/llvm/test/Other/new-pm-thinlto-postlink-pgo-defaults.ll
@@ -110,6 +110,7 @@
; CHECK-O-NEXT: Running pass: LICM
; CHECK-O-NEXT: Running pass: SimpleLoopUnswitchPass
; CHECK-O-NEXT: Running analysis: OuterAnalysisManagerProxy
+; CHECK-O-NEXT: Running pass: LoopFlattenPass
; CHECK-O-NEXT: Running pass: SimplifyCFGPass
; CHECK-O-NEXT: Running pass: InstCombinePass
; CHECK-O-NEXT: Running pass: LoopSimplifyPass
diff --git a/llvm/test/Other/new-pm-thinlto-postlink-samplepgo-defaults.ll b/llvm/test/Other/new-pm-thinlto-postlink-samplepgo-defaults.ll
index 64344aa41b7aa..687011ef68b17 100644
--- a/llvm/test/Other/new-pm-thinlto-postlink-samplepgo-defaults.ll
+++ b/llvm/test/Other/new-pm-thinlto-postlink-samplepgo-defaults.ll
@@ -119,6 +119,7 @@
; CHECK-O-NEXT: Running pass: LICM
; CHECK-O-NEXT: Running pass: SimpleLoopUnswitchPass
; CHECK-O-NEXT: Running analysis: OuterAnalysisManagerProxy
+; CHECK-O-NEXT: Running pass: LoopFlattenPass
; CHECK-O-NEXT: Running pass: SimplifyCFGPass
; CHECK-O-NEXT: Running pass: InstCombinePass
; CHECK-O-NEXT: Running pass: LoopSimplifyPass
diff --git a/llvm/test/Other/new-pm-thinlto-prelink-pgo-defaults.ll b/llvm/test/Other/new-pm-thinlto-prelink-pgo-defaults.ll
index 812212d56bb05..bc3f523658de1 100644
--- a/llvm/test/Other/new-pm-thinlto-prelink-pgo-defaults.ll
+++ b/llvm/test/Other/new-pm-thinlto-prelink-pgo-defaults.ll
@@ -148,6 +148,7 @@
; CHECK-O-NEXT: Running pass: LICM
; CHECK-O-NEXT: Running pass: SimpleLoopUnswitchPass
; CHECK-O-NEXT: Running analysis: OuterAnalysisManagerProxy
+; CHECK-O-NEXT: Running pass: LoopFlattenPass
; CHECK-O-NEXT: Running pass: SimplifyCFGPass
; CHECK-O-NEXT: Running pass: InstCombinePass
; CHECK-O-NEXT: Running pass: LoopSimplifyPass
diff --git a/llvm/test/Other/new-pm-thinlto-prelink-samplepgo-defaults.ll b/llvm/test/Other/new-pm-thinlto-prelink-samplepgo-defaults.ll
index 0d51942672397..1275d2df3f20c 100644
--- a/llvm/test/Other/new-pm-thinlto-prelink-samplepgo-defaults.ll
+++ b/llvm/test/Other/new-pm-thinlto-prelink-samplepgo-defaults.ll
@@ -114,6 +114,7 @@
; CHECK-O-NEXT: Running pass: LICM
; CHECK-O-NEXT: Running pass: SimpleLoopUnswitchPass
; CHECK-O-NEXT: Running analysis: OuterAnalysisManagerProxy
+; CHECK-O-NEXT: Running pass: LoopFlattenPass
; CHECK-O-NEXT: Running pass: SimplifyCFGPass
; CHECK-O-NEXT: Running pass: InstCombinePass
; CHECK-O-NEXT: Running pass: LoopSimplifyPass
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