[ORC][MIPS] Setup t9 register and call function through this register

MIPS ABI states that every function must be called through jalr $t9. In
other words, a function expect that t9 register points to the beginning
of its code. A function uses this register to calculate offset to the
Global Offset Table and save it to the `gp` register.
```
lui   $gp, %hi(_gp_disp)
addiu $gp, %lo(_gp_disp)
addu  $gp, $gp, $t9
```

If `t9` and as a result `$gp` point to the wrong place the following code
loads incorrect value from GOT and passes control to invalid code.
```
lw    $v0,%call16(foo)($gp)
jalr  $t9
```

OrcMips32 and OrcMips64 writeResolverCode methods pass control to the
resolved address, but do not setup `$t9` before the call. The `t9` holds
value of the beginning of `resolver` code so any attempts to call
routines via GOT failed.

This change fixes the problem. The `OrcLazy/hidden-visibility.ll` test
starts to pass correctly. Before the change it fails on MIPS because the
`exitOnLazyCallThroughFailure` called from the resolver code could not
call libc routine `exit` via GOT.

Differential Revision: http://reviews.llvm.org/D56058

llvm-svn: 351000

1 files changed, 8 insertions, 11 deletions

diff --git a/llvm/lib/ExecutionEngine/Orc/OrcABISupport.cpp b/llvm/lib/ExecutionEngine/Orc/OrcABISupport.cpp
index 47499243e0c..3f513e42ef0 100644
--- a/llvm/lib/ExecutionEngine/Orc/OrcABISupport.cpp
+++ b/llvm/lib/ExecutionEngine/Orc/OrcABISupport.cpp
@@ -610,23 +610,19 @@ void OrcMips32_Base::writeResolverCode(uint8_t *ResolverMem,
       0x8fa40008,                    // 0xe8: lw $a0,8($sp)
       0x27bd0068,                    // 0xec: addiu $sp,$sp,104
       0x0300f825,                    // 0xf0: move $ra, $t8
-      0x00000000                     // 0xf4: jr $v0/v1
+      0x00000000,                    // 0xf4: move $t9, $v0/v1
+      0x03200008                     // 0xf8: jr $t9
   };
 
   const unsigned ReentryFnAddrOffset = 0x7c;   // JIT re-entry fn addr lui
   const unsigned CallbackMgrAddrOffset = 0x6c; // Callback manager addr lui
-  const unsigned offsett = 0xf4;
+  const unsigned Offsett = 0xf4;
 
   memcpy(ResolverMem, ResolverCode, sizeof(ResolverCode));
 
-  //Depending on endian return value will be in v0 or v1.
-  uint32_t JumpV0 = 0x00400008;
-  uint32_t JumpV1 = 0x00600008;
-
-  if(isBigEndian == true)
-    memcpy(ResolverMem + offsett, &JumpV1, sizeof(JumpV1));
-  else
-    memcpy(ResolverMem + offsett, &JumpV0, sizeof(JumpV0));
+  // Depending on endian return value will be in v0 or v1.
+  uint32_t MoveVxT9 = isBigEndian ? 0x0060c825 : 0x0040c825;
+  memcpy(ResolverMem + Offsett, &MoveVxT9, sizeof(MoveVxT9));
 
   uint64_t CallMgrAddr = reinterpret_cast<uint64_t>(CallbackMgr);
   uint32_t CallMgrLUi = 0x3c040000 | (((CallMgrAddr + 0x8000) >> 16) & 0xFFFF);
@@ -814,7 +810,8 @@ void OrcMips64::writeResolverCode(uint8_t *ResolverMem, JITReentryFn ReentryFn,
       0xdfa30008,                     // 0x10c: ld v1, 8(sp)
       0x67bd00d0,                     // 0x110: daddiu $sp,$sp,208
       0x0300f825,                     // 0x114: move $ra, $t8
-      0x00400008                      // 0x118: jr $v0
+      0x0040c825,                     // 0x118: move $t9, $v0
+      0x03200008                      // 0x11c: jr $t9
   };
 
   const unsigned ReentryFnAddrOffset = 0x8c;   // JIT re-entry fn addr lui