BasicAA was making the assumption that a local allocation which hadn't escaped

couldn't ever be the return of call instruction. However, it's quite possible
that said local allocation is itself the return of a function call. That's
what malloc and calloc are for, actually.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@64442 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Analysis/BasicAliasAnalysis.cpp b/lib/Analysis/BasicAliasAnalysis.cpp
index 1b26dc421ce3786e6deada1ac47ef49525b8bb75..ef918507b7700110bbcf3079c1143a3b5c559557 100644 (file)
--- a/lib/Analysis/BasicAliasAnalysis.cpp
+++ b/lib/Analysis/BasicAliasAnalysis.cpp
@@ -319,7 +319,7 @@ BasicAliasAnalysis::getModRefInfo(CallSite CS, Value *P, unsigned Size) {
     // If the pointer is to a locally allocated object that does not escape,
     // then the call can not mod/ref the pointer unless the call takes the
     // argument without capturing it.
-    if (isNonEscapingLocalObject(Object)) {
+    if (isNonEscapingLocalObject(Object) && CS.getInstruction() != Object) {
       bool passedAsArg = false;
       // TODO: Eventually only check 'nocapture' arguments.
       for (CallSite::arg_iterator CI = CS.arg_begin(), CE = CS.arg_end();
@@ -414,10 +414,10 @@ BasicAliasAnalysis::alias(const Value *V1, unsigned V1Size,
   // non-escaping local object, then we know the object couldn't escape to a
   // point where the call could return it.
   if ((isa<CallInst>(O1) || isa<InvokeInst>(O1)) &&
-      isNonEscapingLocalObject(O2))
+      isNonEscapingLocalObject(O2) && O1 != O2)
     return NoAlias;
   if ((isa<CallInst>(O2) || isa<InvokeInst>(O2)) &&
-      isNonEscapingLocalObject(O1))
+      isNonEscapingLocalObject(O1) && O1 != O2)
     return NoAlias;
   
   // If we have two gep instructions with must-alias'ing base pointers, figure

diff --git a/test/Analysis/BasicAA/2009-02-12-GEPNoalias.ll b/test/Analysis/BasicAA/2009-02-12-GEPNoalias.ll
new file mode 100644 (file)
index 0000000..93f4f6f
--- /dev/null
+++ b/test/Analysis/BasicAA/2009-02-12-GEPNoalias.ll
@@ -0,0 +1,196 @@
+; RUN: llvm-as < %s | opt -gvn -debug |& grep {REMOVING NONLOCAL LOAD} | count 1
+
+; The bug this is testing for is that BasicAA considered:
+;   alias(%a = noalias call, %b = gep(%a, %unknown))
+; to be NoAlias instead of MayAlias.
+
+@.str = external constant [3 x i8]             ; <[3 x i8]*> [#uses=1]
+@.str1 = external constant [23 x i8]           ; <[23 x i8]*> [#uses=1]
+
+define i32 @main(i32 %argc, i8** nocapture %argv) nounwind {
+entry:
+       %0 = tail call i8* @calloc(i32 11, i32 4) nounwind              ; <i8*> [#uses=1]
+       %1 = bitcast i8* %0 to i32*             ; <i32*> [#uses=7]
+       %2 = tail call i8* @calloc(i32 11, i32 4) nounwind              ; <i8*> [#uses=2]
+       %3 = bitcast i8* %2 to i32*             ; <i32*> [#uses=9]
+       %4 = tail call i8* @calloc(i32 11, i32 4) nounwind              ; <i8*> [#uses=1]
+       %5 = bitcast i8* %4 to i32*             ; <i32*> [#uses=3]
+       br label %bb3.i
+
+bb3.i:         ; preds = %bb3.i, %entry
+       %i.0.reg2mem.0.i = phi i32 [ 0, %entry ], [ %7, %bb3.i ]                ; <i32> [#uses=3]
+       %6 = getelementptr i32* %3, i32 %i.0.reg2mem.0.i                ; <i32*> [#uses=1]
+       store i32 %i.0.reg2mem.0.i, i32* %6, align 4
+       %7 = add i32 %i.0.reg2mem.0.i, 1                ; <i32> [#uses=2]
+       %8 = icmp slt i32 %7, 11                ; <i1> [#uses=1]
+       br i1 %8, label %bb3.i, label %bb8.i.loopexit
+
+bb5.i:         ; preds = %bb29.i
+       %9 = icmp sgt i32 %didpr.1.reg2mem.0.ph.i.ph, 29                ; <i1> [#uses=1]
+       br i1 %9, label %bb11.i.outer, label %bb8.loopexit21.i
+
+bb8.loopexit21.i:              ; preds = %bb5.i
+       %phitmp = add i32 %didpr.1.reg2mem.0.ph.i.ph, 1         ; <i32> [#uses=1]
+       br label %bb8.i.outer
+
+bb8.i.loopexit:                ; preds = %bb3.i
+       br label %bb8.i.outer
+
+bb8.i.outer:           ; preds = %bb8.i.loopexit, %bb8.loopexit21.i
+       %didpr.1.reg2mem.0.ph.i.ph = phi i32 [ %phitmp, %bb8.loopexit21.i ], [ 1, %bb8.i.loopexit ]             ; <i32> [#uses=2]
+       %r.1.reg2mem.0.ph.i.ph = phi i32 [ %r.2.i, %bb8.loopexit21.i ], [ 11, %bb8.i.loopexit ]         ; <i32> [#uses=1]
+       %flipsMax.1.reg2mem.0.ph.i.ph = phi i32 [ %flipsMax.0.ph.i.ph, %bb8.loopexit21.i ], [ 0, %bb8.i.loopexit ]              ; <i32> [#uses=1]
+       br label %bb8.i
+
+bb8.i:         ; preds = %bb8.i, %bb8.i.outer
+       %i.1.reg2mem.0.i = phi i32 [ %14, %bb8.i ], [ 0, %bb8.i.outer ]         ; <i32> [#uses=2]
+       %10 = getelementptr i32* %3, i32 %i.1.reg2mem.0.i               ; <i32*> [#uses=1]
+       %11 = load i32* %10, align 4            ; <i32> [#uses=1]
+       %12 = add i32 %11, 1            ; <i32> [#uses=1]
+       %13 = tail call i32 (i8*, ...)* @printf(i8* noalias getelementptr ([3 x i8]* @.str, i32 0, i32 0), i32 %12) nounwind            ; <i32> [#uses=0]
+       %14 = add i32 %i.1.reg2mem.0.i, 1               ; <i32> [#uses=2]
+       %15 = icmp slt i32 %14, 11              ; <i1> [#uses=1]
+       br i1 %15, label %bb8.i, label %bb9.i
+
+bb9.i:         ; preds = %bb8.i
+       %16 = tail call i32 @putchar(i32 10) nounwind           ; <i32> [#uses=0]
+       br label %bb11.i.outer
+
+bb11.i.outer:          ; preds = %bb9.i, %bb5.i
+       %flipsMax.1.reg2mem.1.ph.i.ph = phi i32 [ %flipsMax.1.reg2mem.0.ph.i.ph, %bb9.i ], [ %flipsMax.0.ph.i.ph, %bb5.i ]              ; <i32> [#uses=4]
+       %r.0.i.ph = phi i32 [ %r.1.reg2mem.0.ph.i.ph, %bb9.i ], [ %r.2.i, %bb5.i ]              ; <i32> [#uses=1]
+       br label %bb11.i
+
+bb10.i:                ; preds = %bb11.i
+       %17 = add i32 %r.0.i, -1                ; <i32> [#uses=1]
+       %18 = getelementptr i32* %5, i32 %17            ; <i32*> [#uses=1]
+       store i32 %r.0.i, i32* %18, align 4
+       %19 = add i32 %r.0.i, -1                ; <i32> [#uses=1]
+       br label %bb11.i
+
+bb11.i:                ; preds = %bb10.i, %bb11.i.outer
+       %r.0.i = phi i32 [ %19, %bb10.i ], [ %r.0.i.ph, %bb11.i.outer ]         ; <i32> [#uses=5]
+       %20 = icmp eq i32 %r.0.i, 1             ; <i1> [#uses=1]
+       br i1 %20, label %bb12.i, label %bb10.i
+
+bb12.i:                ; preds = %bb11.i
+       %21 = load i32* %3, align 4             ; <i32> [#uses=1]
+       %22 = icmp eq i32 %21, 0                ; <i1> [#uses=1]
+       br i1 %22, label %bb24.i.preheader, label %bb13.i
+
+bb13.i:                ; preds = %bb12.i
+       %23 = getelementptr i8* %2, i32 40              ; <i8*> [#uses=1]
+       %24 = bitcast i8* %23 to i32*           ; <i32*> [#uses=1]
+       %25 = load i32* %24, align 4            ; <i32> [#uses=1]
+       %26 = icmp eq i32 %25, 10               ; <i1> [#uses=1]
+       br i1 %26, label %bb24.i.preheader, label %bb16.i.preheader
+
+bb16.i.preheader:              ; preds = %bb13.i
+       br label %bb16.i
+
+bb16.i:                ; preds = %bb16.i, %bb16.i.preheader
+       %i.2.reg2mem.0.i = phi i32 [ %30, %bb16.i ], [ 1, %bb16.i.preheader ]           ; <i32> [#uses=3]
+       %27 = getelementptr i32* %3, i32 %i.2.reg2mem.0.i               ; <i32*> [#uses=1]
+       %28 = load i32* %27, align 4            ; <i32> [#uses=1]
+       %29 = getelementptr i32* %1, i32 %i.2.reg2mem.0.i               ; <i32*> [#uses=1]
+       store i32 %28, i32* %29, align 4
+       %30 = add i32 %i.2.reg2mem.0.i, 1               ; <i32> [#uses=2]
+       %31 = icmp slt i32 %30, 11              ; <i1> [#uses=1]
+       br i1 %31, label %bb16.i, label %bb17.i
+
+bb17.i:                ; preds = %bb16.i
+       %32 = load i32* %3, align 4             ; <i32> [#uses=2]
+       br label %bb20.i.outer
+
+bb20.i.outer:          ; preds = %bb21.i, %bb17.i
+       %k.0.ph.i.ph = phi i32 [ %32, %bb17.i ], [ %43, %bb21.i ]               ; <i32> [#uses=3]
+       %flips.0.ph.i.ph = phi i32 [ 0, %bb17.i ], [ %41, %bb21.i ]             ; <i32> [#uses=1]
+       %j.0.in.i.ph = phi i32 [ %32, %bb17.i ], [ %43, %bb21.i ]               ; <i32> [#uses=1]
+       br label %bb20.i
+
+bb19.i:                ; preds = %bb20.i
+       %33 = getelementptr i32* %1, i32 %i.3.i         ; <i32*> [#uses=1]
+       %34 = load i32* %33, align 4            ; <i32> [#uses=1]
+       %35 = getelementptr i32* %1, i32 %j.0.i         ; <i32*> [#uses=1]
+       %36 = load i32* %35, align 4            ; <i32> [#uses=1]
+       %37 = getelementptr i32* %1, i32 %i.3.i         ; <i32*> [#uses=1]
+       store i32 %36, i32* %37, align 4
+       %38 = getelementptr i32* %1, i32 %j.0.i         ; <i32*> [#uses=1]
+       store i32 %34, i32* %38, align 4
+       %39 = add i32 %i.3.i, 1         ; <i32> [#uses=1]
+       br label %bb20.i
+
+bb20.i:                ; preds = %bb19.i, %bb20.i.outer
+       %i.3.i = phi i32 [ %39, %bb19.i ], [ 1, %bb20.i.outer ]         ; <i32> [#uses=4]
+       %j.0.in.i = phi i32 [ %j.0.i, %bb19.i ], [ %j.0.in.i.ph, %bb20.i.outer ]                ; <i32> [#uses=1]
+       %j.0.i = add i32 %j.0.in.i, -1          ; <i32> [#uses=4]
+       %40 = icmp slt i32 %i.3.i, %j.0.i               ; <i1> [#uses=1]
+       br i1 %40, label %bb19.i, label %bb21.i
+
+bb21.i:                ; preds = %bb20.i
+       %41 = add i32 %flips.0.ph.i.ph, 1               ; <i32> [#uses=3]
+       %42 = getelementptr i32* %1, i32 %k.0.ph.i.ph           ; <i32*> [#uses=1]
+       %43 = load i32* %42, align 4            ; <i32> [#uses=3]
+       %44 = getelementptr i32* %1, i32 %k.0.ph.i.ph           ; <i32*> [#uses=1]
+       store i32 %k.0.ph.i.ph, i32* %44, align 4
+       %45 = icmp eq i32 %43, 0                ; <i1> [#uses=1]
+       br i1 %45, label %bb22.i, label %bb20.i.outer
+
+bb22.i:                ; preds = %bb21.i
+       %46 = icmp slt i32 %flipsMax.1.reg2mem.1.ph.i.ph, %41           ; <i1> [#uses=1]
+       br i1 %46, label %bb23.i, label %bb24.i.preheader
+
+bb23.i:                ; preds = %bb22.i
+       br label %bb24.i.preheader
+
+bb24.i.preheader:              ; preds = %bb23.i, %bb22.i, %bb13.i, %bb12.i
+       %flipsMax.0.ph.i.ph = phi i32 [ %flipsMax.1.reg2mem.1.ph.i.ph, %bb22.i ], [ %flipsMax.1.reg2mem.1.ph.i.ph, %bb13.i ], [ %flipsMax.1.reg2mem.1.ph.i.ph, %bb12.i ], [ %41, %bb23.i ]              ; <i32> [#uses=3]
+       br label %bb24.i
+
+bb24.i:                ; preds = %bb30.i, %bb24.i.preheader
+       %r.2.i = phi i32 [ %60, %bb30.i ], [ %r.0.i, %bb24.i.preheader ]                ; <i32> [#uses=8]
+       %47 = icmp eq i32 %r.2.i, 11            ; <i1> [#uses=1]
+       br i1 %47, label %fannkuch.exit, label %bb26.i
+
+bb26.i:                ; preds = %bb24.i
+       %48 = load i32* %3, align 4             ; <i32> [#uses=1]
+       br label %bb28.i
+
+bb27.i:                ; preds = %bb28.i
+       %49 = add i32 %i.4.i, 1         ; <i32> [#uses=2]
+       %50 = getelementptr i32* %3, i32 %49            ; <i32*> [#uses=1]
+       %51 = load i32* %50, align 4            ; <i32> [#uses=1]
+       %52 = getelementptr i32* %3, i32 %i.4.i         ; <i32*> [#uses=1]
+       store i32 %51, i32* %52, align 4
+       br label %bb28.i
+
+bb28.i:                ; preds = %bb27.i, %bb26.i
+       %i.4.i = phi i32 [ 0, %bb26.i ], [ %49, %bb27.i ]               ; <i32> [#uses=3]
+       %53 = icmp slt i32 %i.4.i, %r.2.i               ; <i1> [#uses=1]
+       br i1 %53, label %bb27.i, label %bb29.i
+
+bb29.i:                ; preds = %bb28.i
+       %54 = getelementptr i32* %3, i32 %r.2.i         ; <i32*> [#uses=1]
+       store i32 %48, i32* %54, align 4
+       %55 = getelementptr i32* %5, i32 %r.2.i         ; <i32*> [#uses=1]
+       %56 = load i32* %55, align 4            ; <i32> [#uses=1]
+       %57 = add i32 %56, -1           ; <i32> [#uses=2]
+       %58 = getelementptr i32* %5, i32 %r.2.i         ; <i32*> [#uses=1]
+       store i32 %57, i32* %58, align 4
+       %59 = icmp sgt i32 %57, 0               ; <i1> [#uses=1]
+       br i1 %59, label %bb5.i, label %bb30.i
+
+bb30.i:                ; preds = %bb29.i
+       %60 = add i32 %r.2.i, 1         ; <i32> [#uses=1]
+       br label %bb24.i
+
+fannkuch.exit:         ; preds = %bb24.i
+       %61 = tail call i32 (i8*, ...)* @printf(i8* noalias getelementptr ([23 x i8]* @.str1, i32 0, i32 0), i32 11, i32 %flipsMax.0.ph.i.ph) nounwind          ; <i32> [#uses=0]
+       ret i32 0
+}
+
+declare noalias i8* @calloc(i32, i32) nounwind
+
+declare i32 @printf(i8* nocapture, ...) nounwind
+
+declare i32 @putchar(i32) nounwind