[GVNHoist] Re-enable GVNHoist by default

My initial motivation for this came from https://reviews.llvm.org/D48122,
where it was pointed out that my change didn't fit well in SimplifyCFG and
therefore using GVNHoist was a better way to go. GVNHoist has been disabled
for a while as there was a list of bugs related to it.

I have fixed the following bugs:

https://bugs.llvm.org/show_bug.cgi?id=37808 -> https://reviews.llvm.org/D48372 (rL337149)
https://bugs.llvm.org/show_bug.cgi?id=36787 -> https://reviews.llvm.org/D49555 (rL337674)
https://bugs.llvm.org/show_bug.cgi?id=37445 -> https://reviews.llvm.org/D49425 (rL337680)

The next two bugs no longer occur, and it's unclear which commit fixed them:

https://bugs.llvm.org/show_bug.cgi?id=36635
https://bugs.llvm.org/show_bug.cgi?id=37791

I investigated this one and proved to be unrelated to GVNHoist, but a genuine bug in NewGvn:

https://bugs.llvm.org/show_bug.cgi?id=37660

To convince myself GVNHoist is in a good state I made a successful bootstrap build of LLVM.
Merging this change now in order to make it to the LLVM 7.0.0 branch.

Differential Revision: https://reviews.llvm.org/D49858

llvm-svn: 338240

lib/Passes/PassBuilder.cpp

@@ -174,8 +174,8 @@ static cl::opt<bool> EnableEarlyCSEMemSSA(
     cl::desc("Enable the EarlyCSE w/ MemorySSA pass for the new PM (default = on)"));
 
 static cl::opt<bool> EnableGVNHoist(
-    "enable-npm-gvn-hoist", cl::init(false), cl::Hidden,
+    "enable-npm-gvn-hoist", cl::init(true), cl::Hidden,
-    cl::desc("Enable the GVN hoisting pass for the new PM (default = off)"));
+    cl::desc("Enable the GVN hoisting pass for the new PM (default = on)"));
 
 static cl::opt<bool> EnableGVNSink(
     "enable-npm-gvn-sink", cl::init(false), cl::Hidden,

lib/Transforms/IPO/PassManagerBuilder.cpp

@@ -135,8 +135,8 @@ static cl::opt<bool> EnableEarlyCSEMemSSA(
     cl::desc("Enable the EarlyCSE w/ MemorySSA pass (default = on)"));
 
 static cl::opt<bool> EnableGVNHoist(
-    "enable-gvn-hoist", cl::init(false), cl::Hidden,
+    "enable-gvn-hoist", cl::init(true), cl::Hidden,
-    cl::desc("Enable the GVN hoisting pass (default = off)"));
+    cl::desc("Enable the GVN hoisting pass (default = on)"));
 
 static cl::opt<bool>
     DisableLibCallsShrinkWrap("disable-libcalls-shrinkwrap", cl::init(false),

test/Other/new-pm-defaults.ll

@@ -121,6 +121,9 @@
 ; CHECK-O-NEXT: Running pass: SROA
 ; CHECK-O-NEXT: Running pass: EarlyCSEPass
 ; CHECK-O-NEXT: Running analysis: MemorySSAAnalysis
+; CHECK-O-NEXT: Running pass: GVNHoistPass on foo
+; CHECK-O-NEXT: Running analysis: PostDominatorTreeAnalysis on foo
+; CHECK-O-NEXT: Running analysis: MemoryDependenceAnalysis on foo
 ; CHECK-O-NEXT: Running pass: SpeculativeExecutionPass
 ; CHECK-O-NEXT: Running pass: JumpThreadingPass
 ; CHECK-O-NEXT: Running analysis: LazyValueAnalysis
@@ -169,18 +172,13 @@
 ; CHECK-O-NEXT: Finished Loop pass manager run.
 ; CHECK-Os-NEXT: Running pass: MergedLoadStoreMotionPass
 ; CHECK-Os-NEXT: Running pass: GVN
-; CHECK-Os-NEXT: Running analysis: MemoryDependenceAnalysis
 ; CHECK-Oz-NEXT: Running pass: MergedLoadStoreMotionPass
 ; CHECK-Oz-NEXT: Running pass: GVN
-; CHECK-Oz-NEXT: Running analysis: MemoryDependenceAnalysis
 ; CHECK-O2-NEXT: Running pass: MergedLoadStoreMotionPass
 ; CHECK-O2-NEXT: Running pass: GVN
-; CHECK-O2-NEXT: Running analysis: MemoryDependenceAnalysis
 ; CHECK-O3-NEXT: Running pass: MergedLoadStoreMotionPass
 ; CHECK-O3-NEXT: Running pass: GVN
-; CHECK-O3-NEXT: Running analysis: MemoryDependenceAnalysis
 ; CHECK-O-NEXT: Running pass: MemCpyOptPass
-; CHECK-O1-NEXT: Running analysis: MemoryDependenceAnalysis
 ; CHECK-O-NEXT: Running pass: SCCPPass
 ; CHECK-O-NEXT: Running pass: BDCEPass
 ; CHECK-O-NEXT: Running analysis: DemandedBitsAnalysis
@@ -196,7 +194,6 @@
 ; CHECK-O-NEXT: Finished llvm::Function pass manager run.
 ; CHECK-EP-SCALAR-LATE-NEXT: Running pass: NoOpFunctionPass
 ; CHECK-O-NEXT: Running pass: ADCEPass
-; CHECK-O-NEXT: Running analysis: PostDominatorTreeAnalysis
 ; CHECK-O-NEXT: Running pass: SimplifyCFGPass
 ; CHECK-O-NEXT: Running pass: InstCombinePass
 ; CHECK-EP-PEEPHOLE-NEXT: Running pass: NoOpFunctionPass

test/Other/new-pm-thinlto-defaults.ll

@@ -106,6 +106,9 @@
 ; CHECK-O-NEXT: Running pass: SROA
 ; CHECK-O-NEXT: Running pass: EarlyCSEPass
 ; CHECK-O-NEXT: Running analysis: MemorySSAAnalysis
+; CHECK-O-NEXT: Running pass: GVNHoistPass on foo
+; CHECK-O-NEXT: Running analysis: PostDominatorTreeAnalysis on foo
+; CHECK-O-NEXT: Running analysis: MemoryDependenceAnalysis on foo
 ; CHECK-O-NEXT: Running pass: SpeculativeExecutionPass
 ; CHECK-O-NEXT: Running pass: JumpThreadingPass
 ; CHECK-O-NEXT: Running analysis: LazyValueAnalysis
@@ -151,18 +154,13 @@
 ; CHECK-O-NEXT: Finished Loop pass manager run.
 ; CHECK-Os-NEXT: Running pass: MergedLoadStoreMotionPass
 ; CHECK-Os-NEXT: Running pass: GVN
-; CHECK-Os-NEXT: Running analysis: MemoryDependenceAnalysis
 ; CHECK-Oz-NEXT: Running pass: MergedLoadStoreMotionPass
 ; CHECK-Oz-NEXT: Running pass: GVN
-; CHECK-Oz-NEXT: Running analysis: MemoryDependenceAnalysis
 ; CHECK-O2-NEXT: Running pass: MergedLoadStoreMotionPass
 ; CHECK-O2-NEXT: Running pass: GVN
-; CHECK-O2-NEXT: Running analysis: MemoryDependenceAnalysis
 ; CHECK-O3-NEXT: Running pass: MergedLoadStoreMotionPass
 ; CHECK-O3-NEXT: Running pass: GVN
-; CHECK-O3-NEXT: Running analysis: MemoryDependenceAnalysis
 ; CHECK-O-NEXT: Running pass: MemCpyOptPass
-; CHECK-O1-NEXT: Running analysis: MemoryDependenceAnalysis
 ; CHECK-O-NEXT: Running pass: SCCPPass
 ; CHECK-O-NEXT: Running pass: BDCEPass
 ; CHECK-O-NEXT: Running analysis: DemandedBitsAnalysis
@@ -176,7 +174,6 @@
 ; CHECK-O-NEXT: Running pass: LCSSAPass
 ; CHECK-O-NEXT: Finished llvm::Function pass manager run
 ; CHECK-O-NEXT: Running pass: ADCEPass
-; CHECK-O-NEXT: Running analysis: PostDominatorTreeAnalysis
 ; CHECK-O-NEXT: Running pass: SimplifyCFGPass
 ; CHECK-O-NEXT: Running pass: InstCombinePass
 ; CHECK-O-NEXT: Finished llvm::Function pass manager run.

test/Other/opt-O2-pipeline.ll

@@ -58,7 +58,12 @@
 ; CHECK-NEXT:         Function Alias Analysis Results
 ; CHECK-NEXT:         Memory SSA
 ; CHECK-NEXT:         Early CSE w/ MemorySSA
+; CHECK-NEXT:         Post-Dominator Tree Construction
+; CHECK-NEXT:         Function Alias Analysis Results
+; CHECK-NEXT:         Memory Dependence Analysis
+; CHECK-NEXT:         Early GVN Hoisting of Expressions
 ; CHECK-NEXT:         Speculatively execute instructions if target has divergent branches
+; CHECK-NEXT:         Basic Alias Analysis (stateless AA impl)
 ; CHECK-NEXT:         Function Alias Analysis Results
 ; CHECK-NEXT:         Lazy Value Information Analysis
 ; CHECK-NEXT:         Jump Threading

test/Other/opt-O3-pipeline.ll

@@ -61,7 +61,12 @@
 ; CHECK-NEXT:         Function Alias Analysis Results
 ; CHECK-NEXT:         Memory SSA
 ; CHECK-NEXT:         Early CSE w/ MemorySSA
+; CHECK-NEXT:         Post-Dominator Tree Construction
+; CHECK-NEXT:         Function Alias Analysis Results
+; CHECK-NEXT:         Memory Dependence Analysis
+; CHECK-NEXT:         Early GVN Hoist
 ; CHECK-NEXT:         Speculatively execute instructions if target has divergent branches
+; CHECK-NEXT:         Basic Alias Analysis (stateless AA impl)
 ; CHECK-NEXT:         Function Alias Analysis Results
 ; CHECK-NEXT:         Lazy Value Information Analysis
 ; CHECK-NEXT:         Jump Threading

test/Other/opt-Os-pipeline.ll

@@ -58,7 +58,12 @@
 ; CHECK-NEXT:         Function Alias Analysis Results
 ; CHECK-NEXT:         Memory SSA
 ; CHECK-NEXT:         Early CSE w/ MemorySSA
+; CHECK-NEXT:         Post-Dominator Tree Construction
+; CHECK-NEXT:         Function Alias Analysis Results
+; CHECK-NEXT:         Memory Dependence Analysis
+; CHECK-NEXT:         Early GVN Hoisting of Expressions
 ; CHECK-NEXT:         Speculatively execute instructions if target has divergent branches
+; CHECK-NEXT:         Basic Alias Analysis (stateless AA impl)
 ; CHECK-NEXT:         Function Alias Analysis Results
 ; CHECK-NEXT:         Lazy Value Information Analysis
 ; CHECK-NEXT:         Jump Threading