Make PrologEpilogInserter save/restore all callee saved registers

in functions which call __builtin_unwind_init()

__builtin_unwind_init() is an undocumented gcc intrinsic which has this effect,
and is used in libgcc_eh.

Goes part of the way toward fixing PR8541.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@183984 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/include/llvm/IR/Intrinsics.td b/include/llvm/IR/Intrinsics.td
index e252664e45cf2593037db1b5fc3866a355e4eb57..65301876633108e0fb9bec69db2824f85afd3d7e 100644 (file)
--- a/include/llvm/IR/Intrinsics.td
+++ b/include/llvm/IR/Intrinsics.td
@@ -347,6 +347,9 @@ def int_eh_typeid_for : Intrinsic<[llvm_i32_ty], [llvm_ptr_ty], [IntrNoMem]>;
 def int_eh_return_i32 : Intrinsic<[], [llvm_i32_ty, llvm_ptr_ty]>;
 def int_eh_return_i64 : Intrinsic<[], [llvm_i64_ty, llvm_ptr_ty]>;
 
+// __builtin_unwind_init is an undocumented GCC intrinsic that causes all
+// callee-saved registers to be saved and restored (regardless of whether they
+// are used) in the calling function. It is used by libgcc_eh.
 def int_eh_unwind_init: Intrinsic<[]>,
                         GCCBuiltin<"__builtin_unwind_init">;
 

diff --git a/lib/CodeGen/PrologEpilogInserter.cpp b/lib/CodeGen/PrologEpilogInserter.cpp
index 4b301d84ca4beaf853adcbc85d11fe082385497a..9f2cba2195f015505c701f90ef9ea6a875b58f6b 100644 (file)
--- a/lib/CodeGen/PrologEpilogInserter.cpp
+++ b/lib/CodeGen/PrologEpilogInserter.cpp
@@ -29,6 +29,7 @@
 #include "llvm/CodeGen/MachineFrameInfo.h"
 #include "llvm/CodeGen/MachineInstr.h"
 #include "llvm/CodeGen/MachineLoopInfo.h"
+#include "llvm/CodeGen/MachineModuleInfo.h"
 #include "llvm/CodeGen/MachineRegisterInfo.h"
 #include "llvm/CodeGen/RegisterScavenging.h"
 #include "llvm/IR/InlineAsm.h"
@@ -227,7 +228,8 @@ void PEI::calculateCalleeSavedRegisters(MachineFunction &F) {
   std::vector<CalleeSavedInfo> CSI;
   for (unsigned i = 0; CSRegs[i]; ++i) {
     unsigned Reg = CSRegs[i];
-    if (F.getRegInfo().isPhysRegUsed(Reg)) {
+    // Functions which call __builtin_unwind_init get all their registers saved.
+    if (F.getRegInfo().isPhysRegUsed(Reg) || F.getMMI().callsUnwindInit()) {
       // If the reg is modified, save it!
       CSI.push_back(CalleeSavedInfo(Reg));
     }

diff --git a/test/CodeGen/ARM/unwind-init.ll b/test/CodeGen/ARM/unwind-init.ll
new file mode 100644 (file)
index 0000000..11683d5
--- /dev/null
+++ b/test/CodeGen/ARM/unwind-init.ll
@@ -0,0 +1,18 @@
+; RUN: llc -mtriple=armv7-unknown-linux-gnueabi < %s | FileCheck %s
+; Check that all callee-saved registers are saved and restored in functions
+; that call __builtin_unwind_init(). This is its undocumented behavior in gcc,
+; and it is used in compiling libgcc_eh.
+; See also PR8541
+
+declare void @llvm.eh.unwind.init()
+
+define void @calls_unwind_init() {
+  call void @llvm.eh.unwind.init()
+  ret void
+}
+
+; CHECK: calls_unwind_init:
+; CHECK: push    {r4, r5, r6, r7, r8, r9, r10, r11, lr}
+; CHECK: vpush   {d8, d9, d10, d11, d12, d13, d14, d15}
+; CHECK: vpop    {d8, d9, d10, d11, d12, d13, d14, d15}
+; CHECK: pop     {r4, r5, r6, r7, r8, r9, r10, r11, pc}

diff --git a/test/CodeGen/X86/unwind-init.ll b/test/CodeGen/X86/unwind-init.ll
new file mode 100644 (file)
index 0000000..e34178d
--- /dev/null
+++ b/test/CodeGen/X86/unwind-init.ll
@@ -0,0 +1,36 @@
+; RUN: llc -mtriple=x86_64-unknown-linux < %s | FileCheck -check-prefix X8664 %s
+; RUN: llc -mtriple=i686-unknown-linux < %s | FileCheck -check-prefix X8632 %s
+; Check that all callee-saved registers are saved and restored in functions
+; that call __builtin_unwind_init(). This is its undocumented behavior in gcc,
+; and it is used in compiling libgcc_eh.
+; See also PR8541
+
+declare void @llvm.eh.unwind.init()
+
+define void @calls_unwind_init() {
+  call void @llvm.eh.unwind.init()
+  ret void
+}
+
+; X8664: calls_unwind_init:
+; X8664: pushq %rbp
+; X8664: pushq %r15
+; X8664: pushq %r14
+; X8664: pushq %r13
+; X8664: pushq %r12
+; X8664: pushq %rbx
+; X8664: popq %rbx
+; X8664: popq %r12
+; X8664: popq %r13
+; X8664: popq %r14
+; X8664: popq %r15
+
+; X8632: calls_unwind_init:
+; X8632: pushl %ebp
+; X8632: pushl %ebx
+; X8632: pushl %edi
+; X8632: pushl %esi
+; X8632: popl %esi
+; X8632: popl %edi
+; X8632: popl %ebx
+; X8632: popl %ebp