[mips] N64 static relocation model support

This patch makes one change to GOT handling and two changes to N64's
relocation model handling. Furthermore, the jumptable encodings have
been corrected for static N64.

Big GOT handling is now done via a new SDNode MipsGotHi - this node is
unconditionally lowered to an lui instruction.

The first change to N64's relocation handling is the lifting of the
restriction that N64 always uses PIC. Now it is possible to target static
environments.

The second change adds support for 64 bit symbols and enables them by
default. Previously N64 had patterns for sym32 mode only. In this mode all
symbols are assumed to have 32 bit addresses. sym32 mode support
is selectable with attribute 'sym32'. A follow on patch for clang will
add the necessary frontend parameter.

This partially resolves PR/23485.

Thanks to Brooks Davis for reporting the issue!

Reviewers: dsanders, seanbruno, zoran.jovanovic, vkalintiris

Differential Revision: https://reviews.llvm.org/D23652

llvm-svn: 293164

1 files changed, 6 insertions, 0 deletions

diff --git a/llvm/lib/Target/Mips/MipsSubtarget.h b/llvm/lib/Target/Mips/MipsSubtarget.h
index 38d3cee7047..5f6fc7ca3ce 100644
--- a/llvm/lib/Target/Mips/MipsSubtarget.h
+++ b/llvm/lib/Target/Mips/MipsSubtarget.h
@@ -142,6 +142,9 @@ class MipsSubtarget : public MipsGenSubtargetInfo {
   // UseTCCInDIV -- Enables the use of trapping in the assembler.
   bool UseTCCInDIV;
 
+  // Sym32 -- On Mips64 symbols are 32 bits.
+  bool HasSym32;
+
   // HasEVA -- supports EVA ASE.
   bool HasEVA;
 
@@ -229,6 +232,9 @@ public:
   unsigned getGPRSizeInBytes() const { return isGP64bit() ? 8 : 4; }
   bool isPTR64bit() const { return IsPTR64bit; }
   bool isPTR32bit() const { return !IsPTR64bit; }
+  bool hasSym32() const {
+    return (HasSym32 && isABI_N64()) || isABI_N32() || isABI_O32();
+  }
   bool isSingleFloat() const { return IsSingleFloat; }
   bool hasVFPU() const { return HasVFPU; }
   bool inMips16Mode() const { return InMips16Mode; }