Enable recursive inlining. Reduce inlining threshold

back to 200; 400 seems to be too high, loses more than
it gains.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@62107 91177308-0d34-0410-b5e6-96231b3b80d8

3 files changed, 98 insertions, 8 deletions

diff --git a/lib/Transforms/IPO/Inliner.cpp b/lib/Transforms/IPO/Inliner.cpp
index 65c0ace..8d40c9b 100644
--- a/lib/Transforms/IPO/Inliner.cpp
+++ b/lib/Transforms/IPO/Inliner.cpp
@@ -31,8 +31,8 @@ STATISTIC(NumInlined, "Number of functions inlined");
 STATISTIC(NumDeleted, "Number of functions deleted because all callers found");
 
 static cl::opt<int>
-InlineLimit("inline-threshold", cl::Hidden, cl::init(400),
-        cl::desc("Control the amount of inlining to perform (default = 400)"));
+InlineLimit("inline-threshold", cl::Hidden, cl::init(200),
+        cl::desc("Control the amount of inlining to perform (default = 200)"));
 
 Inliner::Inliner(void *ID) 
   : CallGraphSCCPass(ID), InlineThreshold(InlineLimit) {}
@@ -168,8 +168,7 @@ bool Inliner::runOnSCC(const std::vector<CallGraphNode*> &SCC) {
     for (unsigned CSi = 0; CSi != CallSites.size(); ++CSi)
       if (Function *Callee = CallSites[CSi].getCalledFunction()) {
         // Calls to external functions are never inlinable.
-        if (Callee->isDeclaration() ||
-            CallSites[CSi].getInstruction()->getParent()->getParent() ==Callee){
+        if (Callee->isDeclaration()) {
           if (SCC.size() == 1) {
             std::swap(CallSites[CSi], CallSites.back());
             CallSites.pop_back();
@@ -190,7 +189,8 @@ bool Inliner::runOnSCC(const std::vector<CallGraphNode*> &SCC) {
           if (InlineCallIfPossible(CS, CG, SCCFunctions, 
                                    getAnalysis<TargetData>())) {
             // Remove any cached cost info for this caller, as inlining the callee
-            // has increased the size of the caller.
+            // has increased the size of the caller (which may be the same as the
+            // callee).
             resetCachedCostInfo(Caller);
 
             // Remove this call site from the list.  If possible, use 
diff --git a/lib/Transforms/Utils/InlineCost.cpp b/lib/Transforms/Utils/InlineCost.cpp
index 90d72ef..97f0bf8 100644
--- a/lib/Transforms/Utils/InlineCost.cpp
+++ b/lib/Transforms/Utils/InlineCost.cpp
@@ -180,14 +180,12 @@ InlineCost InlineCostAnalyzer::getInlineCost(CallSite CS,
   Function *Callee = CS.getCalledFunction();
   Function *Caller = TheCall->getParent()->getParent();
 
-  // Don't inline a directly recursive call.
-  if (Caller == Callee ||
       // Don't inline functions which can be redefined at link-time to mean
       // something else.
       // FIXME: We allow link-once linkage since in practice all versions of
       // the function have the same body (C++ ODR) - but the LLVM definition
       // of LinkOnceLinkage doesn't require this.
-      (Callee->mayBeOverridden() && !Callee->hasLinkOnceLinkage()) ||
+   if ((Callee->mayBeOverridden() && !Callee->hasLinkOnceLinkage()) ||
       // Don't inline functions marked noinline.
       Callee->hasFnAttr(Attribute::NoInline) || NeverInline.count(Callee))
     return llvm::InlineCost::getNever();
diff --git a/test/Transforms/Inline/2009-01-12-RecursiveInline.ll b/test/Transforms/Inline/2009-01-12-RecursiveInline.ll
new file mode 100644
index 0000000..8a4b2e0
--- /dev/null
+++ b/test/Transforms/Inline/2009-01-12-RecursiveInline.ll
@@ -0,0 +1,92 @@
+; RUN: llvm-as < %s | opt -inline | llvm-dis | grep {call.*fib} | count 4
+; First call to fib from fib is inlined, producing 2 instead of 1, total 3.
+; Second call to fib from fib is not inlined because new body of fib exceeds
+; inlining limit of 200.  Plus call in main = 4 total.
+
+; ModuleID = '<stdin>'
+target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:128:128"
+target triple = "i386-apple-darwin9.6"
+@"\01LC" = internal constant [5 x i8] c"%ld\0A\00"		; <[5 x i8]*> [#uses=1]
+
+define i32 @fib(i32 %n) nounwind {
+entry:
+	%n_addr = alloca i32		; <i32*> [#uses=4]
+	%retval = alloca i32		; <i32*> [#uses=2]
+	%0 = alloca i32		; <i32*> [#uses=3]
+	%"alloca point" = bitcast i32 0 to i32		; <i32> [#uses=0]
+	store i32 %n, i32* %n_addr
+	%1 = load i32* %n_addr, align 4		; <i32> [#uses=1]
+	%2 = icmp ule i32 %1, 1		; <i1> [#uses=1]
+	br i1 %2, label %bb, label %bb1
+
+bb:		; preds = %entry
+	store i32 1, i32* %0, align 4
+	br label %bb2
+
+bb1:		; preds = %entry
+	%3 = load i32* %n_addr, align 4		; <i32> [#uses=1]
+	%4 = sub i32 %3, 2		; <i32> [#uses=1]
+	%5 = call i32 @fib(i32 %4) nounwind		; <i32> [#uses=1]
+	%6 = load i32* %n_addr, align 4		; <i32> [#uses=1]
+	%7 = sub i32 %6, 1		; <i32> [#uses=1]
+	%8 = call i32 @fib(i32 %7) nounwind		; <i32> [#uses=1]
+	%9 = add i32 %5, %8		; <i32> [#uses=1]
+	store i32 %9, i32* %0, align 4
+	br label %bb2
+
+bb2:		; preds = %bb1, %bb
+	%10 = load i32* %0, align 4		; <i32> [#uses=1]
+	store i32 %10, i32* %retval, align 4
+	br label %return
+
+return:		; preds = %bb2
+	%retval3 = load i32* %retval		; <i32> [#uses=1]
+	ret i32 %retval3
+}
+
+define i32 @main(i32 %argc, i8** %argv) nounwind {
+entry:
+	%argc_addr = alloca i32		; <i32*> [#uses=2]
+	%argv_addr = alloca i8**		; <i8***> [#uses=2]
+	%retval = alloca i32		; <i32*> [#uses=2]
+	%N = alloca i32		; <i32*> [#uses=2]
+	%0 = alloca i32		; <i32*> [#uses=2]
+	%iftmp.0 = alloca i32		; <i32*> [#uses=3]
+	%"alloca point" = bitcast i32 0 to i32		; <i32> [#uses=0]
+	store i32 %argc, i32* %argc_addr
+	store i8** %argv, i8*** %argv_addr
+	%1 = load i32* %argc_addr, align 4		; <i32> [#uses=1]
+	%2 = icmp eq i32 %1, 2		; <i1> [#uses=1]
+	br i1 %2, label %bb, label %bb1
+
+bb:		; preds = %entry
+	%3 = load i8*** %argv_addr, align 4		; <i8**> [#uses=1]
+	%4 = getelementptr i8** %3, i32 1		; <i8**> [#uses=1]
+	%5 = load i8** %4, align 4		; <i8*> [#uses=1]
+	%6 = call i32 @atoi(i8* %5) nounwind		; <i32> [#uses=1]
+	store i32 %6, i32* %iftmp.0, align 4
+	br label %bb2
+
+bb1:		; preds = %entry
+	store i32 43, i32* %iftmp.0, align 4
+	br label %bb2
+
+bb2:		; preds = %bb1, %bb
+	%7 = load i32* %iftmp.0, align 4		; <i32> [#uses=1]
+	store i32 %7, i32* %N, align 4
+	%8 = load i32* %N, align 4		; <i32> [#uses=1]
+	%9 = call i32 @fib(i32 %8) nounwind		; <i32> [#uses=1]
+	%10 = call i32 (i8*, ...)* @printf(i8* getelementptr ([5 x i8]* @"\01LC", i32 0, i32 0), i32 %9) nounwind		; <i32> [#uses=0]
+	store i32 0, i32* %0, align 4
+	%11 = load i32* %0, align 4		; <i32> [#uses=1]
+	store i32 %11, i32* %retval, align 4
+	br label %return
+
+return:		; preds = %bb2
+	%retval3 = load i32* %retval		; <i32> [#uses=1]
+	ret i32 %retval3
+}
+
+declare i32 @atoi(i8*)
+
+declare i32 @printf(i8*, ...) nounwind