Implement rdar://6295824 and PR6724 with two tiny changes

that can have a big effect :).  The first is to enable the
iterative SCC passmanager juice that kicks in when the
scc passmgr detects that a function pass has devirtualized
a call.  In this case, it will rerun all the passes it 
manages on the SCC, up to the iteration count limit (4). This
is useful because a function pass may devirualize a call, and
we want the inliner to inline it, or pruneeh to infer stuff
about it, etc.

The second patch is to add *all* call sites to the 
DevirtualizedCalls list the inliner uses.  This list is
about to get renamed, but the jist of this is that the 
inliner now reconsiders *all* inlined call sites as candidates
for further inlining.  The intuition is this that in cases 
like this:

f() { g(1); }     g(int x) { h(x); }

We analyze this bottom up, and may decide that it isn't 
profitable to inline H into G.  Next step, we decide that it is
profitable to inline G into F, and do so, which means that F 
now calls H.  Even though the call from G -> H may not have been
profitable to inline, the call from F -> H may be (in this case
because a constant allows folding etc).

In my spot checks, this doesn't have a big impact on code.  For
example, the LLC output for 252.eon grew from 0.02% (from
317252 to 317308) and 176.gcc actually shrunk by .3% (from 1525612
to 1520964 bytes).  252.eon never iterated in the SCC Passmgr,
176.gcc iterated at most 1 time.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@102823 91177308-0d34-0410-b5e6-96231b3b80d8

3 files changed, 184 insertions, 1 deletions

diff --git a/lib/Analysis/IPA/CallGraphSCCPass.cpp b/lib/Analysis/IPA/CallGraphSCCPass.cpp
index 917aa99..288a7ef 100644
--- a/lib/Analysis/IPA/CallGraphSCCPass.cpp
+++ b/lib/Analysis/IPA/CallGraphSCCPass.cpp
@@ -30,7 +30,7 @@
 using namespace llvm;
 
 static cl::opt<unsigned> 
-MaxIterations("max-cg-scc-iterations", cl::ReallyHidden, cl::init(0));
+MaxIterations("max-cg-scc-iterations", cl::ReallyHidden, cl::init(4));
 
 STATISTIC(MaxSCCIterations, "Maximum CGSCCPassMgr iterations on one SCC");
 
diff --git a/lib/Transforms/Utils/InlineFunction.cpp b/lib/Transforms/Utils/InlineFunction.cpp
index 481cacf..c30f514 100644
--- a/lib/Transforms/Utils/InlineFunction.cpp
+++ b/lib/Transforms/Utils/InlineFunction.cpp
@@ -219,6 +219,7 @@ static void UpdateCallGraphAfterInlining(CallSite CS,
       }
     
     CallerNode->addCalledFunction(CallSite::get(NewCall), I->second);
+    IFI.DevirtualizedCalls.push_back(NewCall);
   }
   
   // Update the call graph by deleting the edge from Callee to Caller.  We must
diff --git a/test/Transforms/Inline/devirtualize.ll b/test/Transforms/Inline/devirtualize.ll
new file mode 100644
index 0000000..9ed4b69
--- /dev/null
+++ b/test/Transforms/Inline/devirtualize.ll
@@ -0,0 +1,182 @@
+; RUN: opt -S -inline -scalarrepl -instcombine -simplifycfg -instcombine -gvn -globaldce %s | FileCheck %s
+target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64"
+target triple = "x86_64-apple-darwin10.0.0"
+
+
+; Simple devirt testcase, requires iteration between inliner and GVN.
+;  rdar://6295824
+define i32 @foo(i32 ()** noalias %p, i64* noalias %q) nounwind ssp {
+entry:
+  store i32 ()* @bar, i32 ()** %p
+  store i64 0, i64* %q
+  %tmp3 = load i32 ()** %p                        ; <i32 ()*> [#uses=1]
+  %call = call i32 %tmp3()                        ; <i32> [#uses=1]
+  %X = add i32 %call, 4
+  ret i32 %X
+  
+; CHECK: @foo
+; CHECK-NEXT: entry:
+; CHECK-NEXT: store
+; CHECK-NEXT: store
+; CHECK-NEXT: ret i32 11
+}
+
+define internal i32 @bar() nounwind ssp {
+entry:
+  ret i32 7
+}
+
+
+;; More complex devirt case, from PR6724
+; CHECK: @_Z1gv()
+; CHECK-NEXT: entry:
+; CHECK-NEXT: ret i32 7
+
+%0 = type { i8*, i8* }
+%1 = type { i8*, i8*, i32, i32, i8*, i64, i8*, i64 }
+%2 = type { i8*, i8*, i8* }
+%struct.A = type { i8** }
+%struct.B = type { i8** }
+%struct.C = type { [16 x i8] }
+%struct.D = type { [16 x i8] }
+
+@_ZTV1D = linkonce_odr constant [6 x i8*] [i8* null, i8* bitcast (%2* @_ZTI1D to i8*), i8* bitcast (i32 (%struct.C*)* @_ZN1D1fEv to i8*), i8* inttoptr (i64 -8 to i8*), i8* bitcast (%2* @_ZTI1D to i8*), i8* bitcast (i32 (%struct.C*)* @_ZThn8_N1D1fEv to i8*)] ; <[6 x i8*]*> [#uses=2]
+@_ZTVN10__cxxabiv120__si_class_type_infoE = external global i8* ; <i8**> [#uses=1]
+@_ZTS1D = linkonce_odr constant [3 x i8] c"1D\00"     ; <[3 x i8]*> [#uses=1]
+@_ZTVN10__cxxabiv121__vmi_class_type_infoE = external global i8* ; <i8**> [#uses=1]
+@_ZTS1C = linkonce_odr constant [3 x i8] c"1C\00"     ; <[3 x i8]*> [#uses=1]
+@_ZTVN10__cxxabiv117__class_type_infoE = external global i8* ; <i8**> [#uses=1]
+@_ZTS1A = linkonce_odr constant [3 x i8] c"1A\00"     ; <[3 x i8]*> [#uses=1]
+@_ZTI1A = linkonce_odr constant %0 { i8* bitcast (i8** getelementptr inbounds (i8** @_ZTVN10__cxxabiv117__class_type_infoE, i64 2) to i8*), i8* getelementptr inbounds ([3 x i8]* @_ZTS1A, i32 0, i32 0) } ; <%0*> [#uses=1]
+@_ZTS1B = linkonce_odr constant [3 x i8] c"1B\00"     ; <[3 x i8]*> [#uses=1]
+@_ZTI1B = linkonce_odr constant %0 { i8* bitcast (i8** getelementptr inbounds (i8** @_ZTVN10__cxxabiv117__class_type_infoE, i64 2) to i8*), i8* getelementptr inbounds ([3 x i8]* @_ZTS1B, i32 0, i32 0) } ; <%0*> [#uses=1]
+@_ZTI1C = linkonce_odr constant %1 { i8* bitcast (i8** getelementptr inbounds (i8** @_ZTVN10__cxxabiv121__vmi_class_type_infoE, i64 2) to i8*), i8* getelementptr inbounds ([3 x i8]* @_ZTS1C, i32 0, i32 0), i32 0, i32 2, i8* bitcast (%0* @_ZTI1A to i8*), i64 2, i8* bitcast (%0* @_ZTI1B to i8*), i64 2050 } ; <%1*> [#uses=1]
+@_ZTI1D = linkonce_odr constant %2 { i8* bitcast (i8** getelementptr inbounds (i8** @_ZTVN10__cxxabiv120__si_class_type_infoE, i64 2) to i8*), i8* getelementptr inbounds ([3 x i8]* @_ZTS1D, i32 0, i32 0), i8* bitcast (%1* @_ZTI1C to i8*) } ; <%2*> [#uses=1]
+@_ZTV1C = linkonce_odr constant [6 x i8*] [i8* null, i8* bitcast (%1* @_ZTI1C to i8*), i8* bitcast (i32 (%struct.C*)* @_ZN1C1fEv to i8*), i8* inttoptr (i64 -8 to i8*), i8* bitcast (%1* @_ZTI1C to i8*), i8* bitcast (i32 (%struct.C*)* @_ZThn8_N1C1fEv to i8*)] ; <[6 x i8*]*> [#uses=2]
+@_ZTV1B = linkonce_odr constant [3 x i8*] [i8* null, i8* bitcast (%0* @_ZTI1B to i8*), i8* bitcast (i32 (%struct.A*)* @_ZN1B1fEv to i8*)] ; <[3 x i8*]*> [#uses=1]
+@_ZTV1A = linkonce_odr constant [3 x i8*] [i8* null, i8* bitcast (%0* @_ZTI1A to i8*), i8* bitcast (i32 (%struct.A*)* @_ZN1A1fEv to i8*)] ; <[3 x i8*]*> [#uses=1]
+
+define i32 @_Z1gv() ssp {
+entry:
+  %d = alloca %struct.C, align 8                  ; <%struct.C*> [#uses=2]
+  call void @_ZN1DC1Ev(%struct.C* %d)
+  %call = call i32 @_Z1fP1D(%struct.C* %d)        ; <i32> [#uses=1]
+  %X = add i32 %call, 3
+  ret i32 %X
+}
+
+define linkonce_odr void @_ZN1DC1Ev(%struct.C* %this) inlinehint ssp align 2 {
+entry:
+  call void @_ZN1DC2Ev(%struct.C* %this)
+  ret void
+}
+
+define internal i32 @_Z1fP1D(%struct.C* %d) ssp {
+entry:
+  %0 = icmp eq %struct.C* %d, null                ; <i1> [#uses=1]
+  br i1 %0, label %cast.end, label %cast.notnull
+
+cast.notnull:                                     ; preds = %entry
+  %1 = bitcast %struct.C* %d to i8*               ; <i8*> [#uses=1]
+  %add.ptr = getelementptr i8* %1, i64 8          ; <i8*> [#uses=1]
+  %2 = bitcast i8* %add.ptr to %struct.A*         ; <%struct.A*> [#uses=1]
+  br label %cast.end
+
+cast.end:                                         ; preds = %entry, %cast.notnull
+  %3 = phi %struct.A* [ %2, %cast.notnull ], [ null, %entry ] ; <%struct.A*> [#uses=2]
+  %4 = bitcast %struct.A* %3 to i32 (%struct.A*)*** ; <i32 (%struct.A*)***> [#uses=1]
+  %5 = load i32 (%struct.A*)*** %4                ; <i32 (%struct.A*)**> [#uses=1]
+  %vfn = getelementptr inbounds i32 (%struct.A*)** %5, i64 0 ; <i32 (%struct.A*)**> [#uses=1]
+  %6 = load i32 (%struct.A*)** %vfn               ; <i32 (%struct.A*)*> [#uses=1]
+  %call = call i32 %6(%struct.A* %3)              ; <i32> [#uses=1]
+  ret i32 %call
+}
+
+define linkonce_odr i32 @_ZN1D1fEv(%struct.C* %this) ssp align 2 {
+entry:
+  ret i32 4
+}
+
+define linkonce_odr i32 @_ZThn8_N1D1fEv(%struct.C* %this) {
+entry:
+  %0 = bitcast %struct.C* %this to i8*            ; <i8*> [#uses=1]
+  %1 = getelementptr inbounds i8* %0, i64 -8      ; <i8*> [#uses=1]
+  %2 = bitcast i8* %1 to %struct.C*               ; <%struct.C*> [#uses=1]
+  %call = call i32 @_ZN1D1fEv(%struct.C* %2)      ; <i32> [#uses=1]
+  ret i32 %call
+}
+
+define linkonce_odr void @_ZN1DC2Ev(%struct.C* %this) inlinehint ssp align 2 {
+entry:
+  call void @_ZN1CC2Ev(%struct.C* %this)
+  %0 = bitcast %struct.C* %this to i8*            ; <i8*> [#uses=1]
+  %1 = getelementptr inbounds i8* %0, i64 0       ; <i8*> [#uses=1]
+  %2 = bitcast i8* %1 to i8***                    ; <i8***> [#uses=1]
+  store i8** getelementptr inbounds ([6 x i8*]* @_ZTV1D, i64 0, i64 2), i8*** %2
+  %3 = bitcast %struct.C* %this to i8*            ; <i8*> [#uses=1]
+  %4 = getelementptr inbounds i8* %3, i64 8       ; <i8*> [#uses=1]
+  %5 = bitcast i8* %4 to i8***                    ; <i8***> [#uses=1]
+  store i8** getelementptr inbounds ([6 x i8*]* @_ZTV1D, i64 0, i64 5), i8*** %5
+  ret void
+}
+
+define linkonce_odr void @_ZN1CC2Ev(%struct.C* %this) inlinehint ssp align 2 {
+entry:
+  %0 = bitcast %struct.C* %this to %struct.A*     ; <%struct.A*> [#uses=1]
+  call void @_ZN1AC2Ev(%struct.A* %0)
+  %1 = bitcast %struct.C* %this to i8*            ; <i8*> [#uses=1]
+  %2 = getelementptr inbounds i8* %1, i64 8       ; <i8*> [#uses=1]
+  %3 = bitcast i8* %2 to %struct.A*               ; <%struct.A*> [#uses=1]
+  call void @_ZN1BC2Ev(%struct.A* %3)
+  %4 = bitcast %struct.C* %this to i8*            ; <i8*> [#uses=1]
+  %5 = getelementptr inbounds i8* %4, i64 0       ; <i8*> [#uses=1]
+  %6 = bitcast i8* %5 to i8***                    ; <i8***> [#uses=1]
+  store i8** getelementptr inbounds ([6 x i8*]* @_ZTV1C, i64 0, i64 2), i8*** %6
+  %7 = bitcast %struct.C* %this to i8*            ; <i8*> [#uses=1]
+  %8 = getelementptr inbounds i8* %7, i64 8       ; <i8*> [#uses=1]
+  %9 = bitcast i8* %8 to i8***                    ; <i8***> [#uses=1]
+  store i8** getelementptr inbounds ([6 x i8*]* @_ZTV1C, i64 0, i64 5), i8*** %9
+  ret void
+}
+
+define linkonce_odr i32 @_ZN1C1fEv(%struct.C* %this) ssp align 2 {
+entry:
+  ret i32 3
+}
+
+define linkonce_odr i32 @_ZThn8_N1C1fEv(%struct.C* %this) {
+entry:
+  %0 = bitcast %struct.C* %this to i8*            ; <i8*> [#uses=1]
+  %1 = getelementptr inbounds i8* %0, i64 -8      ; <i8*> [#uses=1]
+  %2 = bitcast i8* %1 to %struct.C*               ; <%struct.C*> [#uses=1]
+  %call = call i32 @_ZN1C1fEv(%struct.C* %2)      ; <i32> [#uses=1]
+  ret i32 %call
+}
+
+define linkonce_odr void @_ZN1AC2Ev(%struct.A* %this) inlinehint ssp align 2 {
+entry:
+  %0 = bitcast %struct.A* %this to i8*            ; <i8*> [#uses=1]
+  %1 = getelementptr inbounds i8* %0, i64 0       ; <i8*> [#uses=1]
+  %2 = bitcast i8* %1 to i8***                    ; <i8***> [#uses=1]
+  store i8** getelementptr inbounds ([3 x i8*]* @_ZTV1A, i64 0, i64 2), i8*** %2
+  ret void
+}
+
+define linkonce_odr void @_ZN1BC2Ev(%struct.A* %this) inlinehint ssp align 2 {
+entry:
+  %0 = bitcast %struct.A* %this to i8*            ; <i8*> [#uses=1]
+  %1 = getelementptr inbounds i8* %0, i64 0       ; <i8*> [#uses=1]
+  %2 = bitcast i8* %1 to i8***                    ; <i8***> [#uses=1]
+  store i8** getelementptr inbounds ([3 x i8*]* @_ZTV1B, i64 0, i64 2), i8*** %2
+  ret void
+}
+
+define linkonce_odr i32 @_ZN1B1fEv(%struct.A* %this) ssp align 2 {
+entry:
+  ret i32 2
+}
+
+define linkonce_odr i32 @_ZN1A1fEv(%struct.A* %this) ssp align 2 {
+entry:
+  ret i32 1
+}