ARM: tail-call inside a function where part of a byval argument is on caller's

local frame causes problem.

For example:
void f(StructToPass s) {
  g(&s, sizeof(s));
}
will cause problem with tail-call since part of s is passed via registers and
saved in f's local frame. When g tries to access s, part of s may be corrupted
since f's local frame is popped out before the tail-call.

The current fix is to disable tail-call if getVarArgsRegSaveSize is not 0 for
the caller. This is a conservative approach, if we can prove the address of
s or part of s is not taken and passed to g, it should be okay to perform
tail-call.

rdar://12442472

llvm-svn: 165853

1 files changed, 44 insertions, 0 deletions

diff --git a/llvm/test/CodeGen/ARM/struct_byval.ll b/llvm/test/CodeGen/ARM/struct_byval.ll
index 99ba475ad7b..e9541c27880 100644
--- a/llvm/test/CodeGen/ARM/struct_byval.ll
+++ b/llvm/test/CodeGen/ARM/struct_byval.ll
@@ -44,3 +44,47 @@ entry:
 declare i32 @e1(%struct.SmallStruct* nocapture byval %in) nounwind
 declare i32 @e2(%struct.LargeStruct* nocapture byval %in) nounwind
 declare i32 @e3(%struct.LargeStruct* nocapture byval align 16 %in) nounwind
+
+; rdar://12442472
+; We can't do tail call since address of s is passed to the callee and part of
+; s is in caller's local frame.
+define void @f3(%struct.SmallStruct* nocapture byval %s) nounwind optsize {
+; CHECK: f3
+; CHECK: bl _consumestruct
+entry:
+  %0 = bitcast %struct.SmallStruct* %s to i8*
+  tail call void @consumestruct(i8* %0, i32 80) optsize
+  ret void
+}
+
+define void @f4(%struct.SmallStruct* nocapture byval %s) nounwind optsize {
+; CHECK: f4
+; CHECK: bl _consumestruct
+entry:
+  %addr = getelementptr inbounds %struct.SmallStruct* %s, i32 0, i32 0
+  %0 = bitcast i32* %addr to i8*
+  tail call void @consumestruct(i8* %0, i32 80) optsize
+  ret void
+}
+
+; We can do tail call here since s is in the incoming argument area.
+define void @f5(i32 %a, i32 %b, i32 %c, i32 %d, %struct.SmallStruct* nocapture byval %s) nounwind optsize {
+; CHECK: f5
+; CHECK: b _consumestruct
+entry:
+  %0 = bitcast %struct.SmallStruct* %s to i8*
+  tail call void @consumestruct(i8* %0, i32 80) optsize
+  ret void
+}
+
+define void @f6(i32 %a, i32 %b, i32 %c, i32 %d, %struct.SmallStruct* nocapture byval %s) nounwind optsize {
+; CHECK: f6
+; CHECK: b _consumestruct
+entry:
+  %addr = getelementptr inbounds %struct.SmallStruct* %s, i32 0, i32 0
+  %0 = bitcast i32* %addr to i8*
+  tail call void @consumestruct(i8* %0, i32 80) optsize
+  ret void
+}
+
+declare void @consumestruct(i8* nocapture %structp, i32 %structsize) nounwind