[FuncSpec] Enable SpecializeLiteralConstant by default

Enable specialization on literal constant arguments by default in
Function Specialization.

Author: hazzlim

llvm/lib/Transforms/IPO/FunctionSpecialization.cpp

@@ -84,14 +84,11 @@ static cl::opt<bool> SpecializeOnAddress(
     "funcspec-on-address", cl::init(false), cl::Hidden, cl::desc(
     "Enable function specialization on the address of global values"));
 
-// Disabled by default as it can significantly increase compilation times.
-//
-// https://llvm-compile-time-tracker.com
-// https://github.com/nikic/llvm-compile-time-tracker
 static cl::opt<bool> SpecializeLiteralConstant(
-    "funcspec-for-literal-constant", cl::init(false), cl::Hidden, cl::desc(
-    "Enable specialization of functions that take a literal constant as an "
-    "argument"));
+    "funcspec-for-literal-constant", cl::init(true), cl::Hidden,
+    cl::desc(
+        "Enable specialization of functions that take a literal constant as an "
+        "argument"));
 
 bool InstCostVisitor::canEliminateSuccessor(BasicBlock *BB, BasicBlock *Succ,
                                          DenseSet<BasicBlock *> &DeadBlocks) {
@@ -682,10 +679,9 @@ bool FunctionSpecializer::run() {
         (RequireMinSize && Metrics.NumInsts < MinFunctionSize))
       continue;
 
-    // TODO: For now only consider recursive functions when running multiple
-    // times. This should change if specialization on literal constants gets
-    // enabled.
-    if (!Inserted && !Metrics.isRecursive && !SpecializeLiteralConstant)
+    // When specialization on literal constants is disabled, only consider
+    // recursive functions when running multiple times.
+    if (!SpecializeLiteralConstant && !Inserted && !Metrics.isRecursive)
       continue;
 
     int64_t Sz = *Metrics.NumInsts.getValue();

llvm/test/DebugInfo/Generic/ipsccp-remap-assign-id.ll

@@ -1,5 +1,5 @@
-; RUN: opt -passes=ipsccp %s -S -o - | FileCheck %s
-; RUN: opt --try-experimental-debuginfo-iterators -passes=ipsccp %s -S -o - | FileCheck %s
+; RUN: opt -passes=ipsccp -funcspec-for-literal-constant=false %s -S -o - | FileCheck %s
+; RUN: opt --try-experimental-debuginfo-iterators -passes=ipsccp -funcspec-for-literal-constant=false %s -S -o - | FileCheck %s
 
 ;; Check the dbg.assign DIAssignID operand gets remapped after cloning.
 

llvm/test/Transforms/FunctionSpecialization/compiler-crash-58759.ll

@@ -1,4 +1,4 @@
-; RUN: opt -S --passes="default<O3>" < %s | FileCheck %s
+; RUN: opt -S --passes="default<O3>" -funcspec-for-literal-constant=false < %s | FileCheck %s
 
 define dso_local i32 @g0(i32 noundef %x) local_unnamed_addr {
 entry:

llvm/test/Transforms/FunctionSpecialization/function-specialization-constant-expression.ll

@@ -4,7 +4,7 @@
 ; Note that this test case shows that function specialization pass would
 ; transform the function even if no specialization happened.
 
-; RUN: opt -passes="ipsccp<func-spec>" -force-specialization -S < %s | FileCheck %s
+; RUN: opt -passes="ipsccp<func-spec>" -force-specialization -funcspec-for-literal-constant=false -S < %s | FileCheck %s
 
 %struct = type { i8, i16, i32, i64, i64}
 @Global = internal constant %struct {i8 0, i16 1, i32 2, i64 3, i64 4}

llvm/test/Transforms/FunctionSpecialization/function-specialization2.ll

@@ -1,7 +1,7 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --include-generated-funcs --version 5
-; RUN: opt -passes="ipsccp<func-spec>,deadargelim" -force-specialization -S < %s | FileCheck %s
-; RUN: opt -passes="ipsccp<func-spec>,deadargelim" -funcspec-max-iters=1 -force-specialization -S < %s | FileCheck %s --check-prefix=ONE-ITER
-; RUN: opt -passes="ipsccp<func-spec>,deadargelim" -funcspec-max-iters=0 -force-specialization -S < %s | FileCheck %s --check-prefix=DISABLED
+; RUN: opt -passes="ipsccp<func-spec>,deadargelim" -funcspec-for-literal-constant=false -force-specialization -S < %s | FileCheck %s
+; RUN: opt -passes="ipsccp<func-spec>,deadargelim" -funcspec-for-literal-constant=false -funcspec-max-iters=1 -force-specialization -S < %s | FileCheck %s --check-prefix=ONE-ITER
+; RUN: opt -passes="ipsccp<func-spec>,deadargelim" -funcspec-for-literal-constant=false -funcspec-max-iters=0 -force-specialization -S < %s | FileCheck %s --check-prefix=DISABLED
 
 
 define internal i32 @func(ptr %0, i32 %1, ptr nocapture %2) {

llvm/test/Transforms/FunctionSpecialization/function-specialization4.ll

@@ -1,8 +1,10 @@
 ; RUN: opt -passes="ipsccp<func-spec>" -force-specialization \
-; RUN:   -funcspec-max-clones=2 -S < %s | FileCheck %s
+; RUN:   -funcspec-for-literal-constant=false -funcspec-max-clones=2 \
+; RUN:   -S < %s | FileCheck %s
 
 ; RUN: opt -passes="ipsccp<func-spec>" -force-specialization \
-; RUN:   -funcspec-max-clones=1 -S < %s | FileCheck %s --check-prefix=CONST1
+; RUN:   -funcspec-for-literal-constant=false -funcspec-max-clones=1 \
+; RUN:   -S < %s | FileCheck %s --check-prefix=CONST1
 
 target datalayout = "e-m:e-i8:8:32-i16:16:32-i64:64-i128:128-n32:64-S128"
 

llvm/test/Transforms/FunctionSpecialization/get-possible-constants.ll

@@ -1,4 +1,4 @@
-; RUN: opt -S --passes="ipsccp<func-spec>" < %s | FileCheck %s
+; RUN: opt -S --passes="ipsccp<func-spec>" -funcspec-for-literal-constant=false < %s | FileCheck %s
 define dso_local i32 @p0(i32 noundef %x) {
 entry:
   %add = add nsw i32 %x, 1

llvm/test/Transforms/FunctionSpecialization/global-rank.ll

@@ -1,4 +1,4 @@
-; RUN: opt -S --passes="ipsccp<func-spec>" -funcspec-max-clones=1 < %s | FileCheck %s
+; RUN: opt -S --passes="ipsccp<func-spec>" -funcspec-for-literal-constant=false -funcspec-max-clones=1 < %s | FileCheck %s
 define internal i32 @f(i32 noundef %x, ptr nocapture noundef readonly %p, ptr nocapture noundef readonly %q) noinline {
 entry:
   %call = tail call i32 %p(i32 noundef %x)

llvm/test/Transforms/FunctionSpecialization/identical-specializations.ll

@@ -1,5 +1,5 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --include-generated-funcs --version 5
-; RUN: opt -passes="ipsccp<func-spec>" -force-specialization -S < %s | FileCheck %s
+; RUN: opt -passes="ipsccp<func-spec>" -force-specialization -funcspec-for-literal-constant=false -S < %s | FileCheck %s
 
 define i64 @main(i64 %x, i64 %y, i1 %flag) {
 entry:

llvm/test/Transforms/FunctionSpecialization/literal-const.ll

@@ -1,7 +1,8 @@
 ; RUN: opt -S --passes="ipsccp<func-spec>" \
+; RUN:        -funcspec-for-literal-constant=false \
 ; RUN:        -force-specialization < %s | FileCheck %s -check-prefix CHECK-NOLIT
 ; RUN: opt -S --passes="ipsccp<func-spec>" \
-; RUN:        -funcspec-for-literal-constant \
+; RUN:        -funcspec-for-literal-constant=true \
 ; RUN:        -force-specialization < %s | FileCheck %s -check-prefix CHECK-LIT
 
 define i32 @f0(i32 noundef %x) {