From c0cc28301a7fa71ae895dd637058e0624f6bd399 Mon Sep 17 00:00:00 2001
From: Quentin Colombet <qcolombet@apple.com>
Date: Sat, 8 Jun 2013 00:07:54 +0000
Subject: [PATCH] Reapply r183552. This time, use a standard type for the
 option to avoid template instantiation issue with non-standard type.

Add a backend option to warn on a given stack size limit.
Option: -mllvm -warn-stack-size=<limit>
Output (if limit is exceeded):
warning: Stack size limit exceeded (<actual size>) in <functionName>.

The longer term plan is to hook that to a clang warning.
PR:4072
<rdar://problem/13987214>.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@183595 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/CodeGen/PrologEpilogInserter.cpp | 13 +++++++++++++
 test/CodeGen/ARM/warn-stack.ll       | 24 ++++++++++++++++++++++++
 test/CodeGen/X86/warn-stack.ll       | 24 ++++++++++++++++++++++++
 3 files changed, 61 insertions(+)
 create mode 100644 test/CodeGen/ARM/warn-stack.ll
 create mode 100644 test/CodeGen/X86/warn-stack.ll

diff --git a/lib/CodeGen/PrologEpilogInserter.cpp b/lib/CodeGen/PrologEpilogInserter.cpp
index 959dd7df58e..4b301d84ca4 100644
--- a/lib/CodeGen/PrologEpilogInserter.cpp
+++ b/lib/CodeGen/PrologEpilogInserter.cpp
@@ -35,6 +35,7 @@
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/Compiler.h"
 #include "llvm/Support/Debug.h"
+#include "llvm/Support/raw_ostream.h"
 #include "llvm/Target/TargetFrameLowering.h"
 #include "llvm/Target/TargetInstrInfo.h"
 #include "llvm/Target/TargetMachine.h"
@@ -46,6 +47,11 @@ using namespace llvm;
 char PEI::ID = 0;
 char &llvm::PrologEpilogCodeInserterID = PEI::ID;
 
+static cl::opt<unsigned>
+WarnStackSize("warn-stack-size", cl::Hidden, cl::init((unsigned)-1),
+              cl::desc("Warn for stack size bigger than the given"
+                       " number"));
+
 INITIALIZE_PASS_BEGIN(PEI, "prologepilog",
                 "Prologue/Epilogue Insertion", false, false)
 INITIALIZE_PASS_DEPENDENCY(MachineLoopInfo)
@@ -128,6 +134,13 @@ bool PEI::runOnMachineFunction(MachineFunction &Fn) {
   // Clear any vregs created by virtual scavenging.
   Fn.getRegInfo().clearVirtRegs();
 
+  // Warn on stack size when we exceeds the given limit.
+  MachineFrameInfo *MFI = Fn.getFrameInfo();
+  if (WarnStackSize.getNumOccurrences() > 0 &&
+      WarnStackSize < MFI->getStackSize())
+    errs() << "warning: Stack size limit exceeded (" << MFI->getStackSize()
+           << ") in " << Fn.getName()  << ".\n";
+
   delete RS;
   clearAllSets();
   return true;
diff --git a/test/CodeGen/ARM/warn-stack.ll b/test/CodeGen/ARM/warn-stack.ll
new file mode 100644
index 00000000000..9538bbf1048
--- /dev/null
+++ b/test/CodeGen/ARM/warn-stack.ll
@@ -0,0 +1,24 @@
+; RUN: llc -mtriple thumbv7-apple-ios3.0.0 -warn-stack-size=80 < %s 2>&1 >/dev/null | FileCheck %s
+; Check the internal option that warns when the stack size exceeds the
+; given amount.
+; <rdar://13987214>
+
+; CHECK-NOT: nowarn
+define void @nowarn() nounwind ssp {
+entry:
+  %buffer = alloca [12 x i8], align 1
+  %arraydecay = getelementptr inbounds [12 x i8]* %buffer, i64 0, i64 0
+  call void @doit(i8* %arraydecay) nounwind
+  ret void
+}
+
+; CHECK: warning: Stack size limit exceeded (96) in warn.
+define void @warn() nounwind ssp {
+entry:
+  %buffer = alloca [80 x i8], align 1
+  %arraydecay = getelementptr inbounds [80 x i8]* %buffer, i64 0, i64 0
+  call void @doit(i8* %arraydecay) nounwind
+  ret void
+}
+
+declare void @doit(i8*)
diff --git a/test/CodeGen/X86/warn-stack.ll b/test/CodeGen/X86/warn-stack.ll
new file mode 100644
index 00000000000..5979f45b07d
--- /dev/null
+++ b/test/CodeGen/X86/warn-stack.ll
@@ -0,0 +1,24 @@
+; RUN: llc -mtriple x86_64-apple-macosx10.8.0 -warn-stack-size=80 < %s 2>&1 >/dev/null | FileCheck %s
+; Check the internal option that warns when the stack size exceeds the
+; given amount.
+; <rdar://13987214>
+
+; CHECK-NOT: nowarn
+define void @nowarn() nounwind ssp {
+entry:
+  %buffer = alloca [12 x i8], align 1
+  %arraydecay = getelementptr inbounds [12 x i8]* %buffer, i64 0, i64 0
+  call void @doit(i8* %arraydecay) nounwind
+  ret void
+}
+
+; CHECK: warning: Stack size limit exceeded (104) in warn.
+define void @warn() nounwind ssp {
+entry:
+  %buffer = alloca [80 x i8], align 1
+  %arraydecay = getelementptr inbounds [80 x i8]* %buffer, i64 0, i64 0
+  call void @doit(i8* %arraydecay) nounwind
+  ret void
+}
+
+declare void @doit(i8*)