Fix PR7272: when inlining through a callsite with byval arguments,

the newly created allocas may be used by inlined calls, so these
need to have their tail call flags cleared.  Fixes PR7272.

llvm-svn: 105255

lib/Transforms/Utils/InlineFunction.cpp

@@ -351,6 +351,10 @@ bool llvm::InlineFunction(CallSite CS, InlineFunctionInfo &IFI) {
         // Uses of the argument in the function should use our new alloca
         // instead.
         ActualArg = NewAlloca;
+
+        // Calls that we inline may use the new alloca, so we need to clear
+        // their 'tail' flags.
+        MustClearTailCallFlags = true;
       }
 
       ValueMap[I] = ActualArg;

test/Transforms/Inline/2010-05-31-ByvalTailcall.ll

@@ -0,0 +1,24 @@
+; RUN: opt < %s -tailcallelim -inline -instcombine -dse -S | FileCheck %s
+; PR7272
+
+; When inlining through a byval call site, the inliner creates allocas which may
+; be used by inlined calls, so any inlined calls need to have their 'tail' flags
+; cleared.  If not then you can get nastiness like with this testcase, where the
+; (inlined) call to 'ext' in 'foo' was being passed an uninitialized value.
+
+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-f80:32:32-n8:16:32"
+target triple = "i386-pc-linux-gnu"
+
+declare void @ext(i32*)
+
+define void @bar(i32* byval %x) {
+  call void @ext(i32* %x)
+  ret void
+}
+
+define void @foo(i32* %x) {
+; CHECK: define void @foo
+; CHECK: store i32 %1, i32* %x
+  call void @bar(i32* byval %x)
+  ret void
+}