[libunwind][MIPS] Support MIPS floating-point registers for hard-float ABIs.

Summary:
For MIPS ABIs with 64-bit floating point registers including newabi
and O32 with 64-bit floating point registers, just save and restore the
32 floating-point registers as doubles.

For O32 MIPS with 32-bit floating-point registers, save and restore the
individual floating-point registers as "plain" registers.  These registers
are encoded as floats rather than doubles, but the DWARF unwinder
assumes that floating-point registers are stored as doubles when reading
them from memory (via AddressSpace::getDouble()).  Treating the
registers as "normal" registers instead causes the DWARF unwinder to
fetch them from memory as a 32-bit register.  This does mean that for
O32 with 32-bit floating-point registers unw_get_fpreg() and
unw_set_fpreg() do not work.  One would have to use unw_get_reg()
and unw_set_reg() instead.  However, DWARF unwinding works
correctly as the DWARF CFI emits records for individual 32-bit
floating-point registers even when they are treated as doubles stored
in paired registers.  If the lack of unw_get/set_fpreg() becomes a pressing
need in the future for O32 MIPS we could add in special handling to
make it work.

Reviewers: sdardis, compnerd

Reviewed By: sdardis

Differential Revision: https://reviews.llvm.org/D41968

llvm-svn: 332414

1 files changed, 32 insertions, 0 deletions

diff --git a/libunwind/include/libunwind.h b/libunwind/include/libunwind.h
index 04e31e8ea4e..8e3d3fe9af2 100644
--- a/libunwind/include/libunwind.h
+++ b/libunwind/include/libunwind.h
@@ -781,6 +781,38 @@ enum {
   UNW_MIPS_R29 = 29,
   UNW_MIPS_R30 = 30,
   UNW_MIPS_R31 = 31,
+  UNW_MIPS_F0  = 32,
+  UNW_MIPS_F1  = 33,
+  UNW_MIPS_F2  = 34,
+  UNW_MIPS_F3  = 35,
+  UNW_MIPS_F4  = 36,
+  UNW_MIPS_F5  = 37,
+  UNW_MIPS_F6  = 38,
+  UNW_MIPS_F7  = 39,
+  UNW_MIPS_F8  = 40,
+  UNW_MIPS_F9  = 41,
+  UNW_MIPS_F10 = 42,
+  UNW_MIPS_F11 = 43,
+  UNW_MIPS_F12 = 44,
+  UNW_MIPS_F13 = 45,
+  UNW_MIPS_F14 = 46,
+  UNW_MIPS_F15 = 47,
+  UNW_MIPS_F16 = 48,
+  UNW_MIPS_F17 = 49,
+  UNW_MIPS_F18 = 50,
+  UNW_MIPS_F19 = 51,
+  UNW_MIPS_F20 = 52,
+  UNW_MIPS_F21 = 53,
+  UNW_MIPS_F22 = 54,
+  UNW_MIPS_F23 = 55,
+  UNW_MIPS_F24 = 56,
+  UNW_MIPS_F25 = 57,
+  UNW_MIPS_F26 = 58,
+  UNW_MIPS_F27 = 59,
+  UNW_MIPS_F28 = 60,
+  UNW_MIPS_F29 = 61,
+  UNW_MIPS_F30 = 62,
+  UNW_MIPS_F31 = 63,
   UNW_MIPS_HI = 64,
   UNW_MIPS_LO = 65,
 };