6502/llvm-6502
1
0
Fork 0
mirror of https://github.com/c64scene-ar/llvm-6502.git synced 2024-12-13 20:32:21 +00:00
Code Issues Projects Releases Wiki Activity

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

Browse Source 
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


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@165853 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Manman Ren 2012-10-12 23:39:43 +00:00
parent 7a2b624bb3
commit e6c3cc8dc5
3 changed files with 57 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
lib/Target/ARM/ARMISelLowering.cpp
View File

@ -1804,6 +1804,14 @@ ARMTargetLowering::IsEligibleForTailCallOptimization(SDValue Callee,
}
}
// If Caller's vararg or byval argument has been split between registers and
// stack, do not perform tail call, since part of the argument is in caller's
// local frame.
const ARMFunctionInfo *AFI_Caller = DAG.getMachineFunction().
getInfo<ARMFunctionInfo>();
if (AFI_Caller->getVarArgsRegSaveSize())
return false;
// If the callee takes no arguments then go on to check the results of the
// call.
if (!Outs.empty()) {

5
test/CodeGen/ARM/2011-06-16-TailCallByVal.ll
View File

@ -1,4 +1,9 @@
; RUN: llc < %s -arm-tail-calls=1 | FileCheck %s
; tail call inside a function where byval argument is splitted between
; registers and stack is currently unsupported.
; XFAIL: *
target datalayout = "e-p:32:32:32-i1:8:32-i8:8:32-i16:16:32-i32:32:32-i64:32:32-f32:32:32-f64:32:32-v64:32:64-v128:32:128-a0:0:32-n32"
target triple = "thumbv7-apple-ios"

44
test/CodeGen/ARM/struct_byval.ll
View File

@ -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