Implement PowerPC 64-bit native code backend for Linux

Extend the PowerPC 32-bit native code generator for "64-bit
PowerPC ELF Application Binary Interface Supplement 1.9" by
Ian Lance Taylor and "Power Architecture 64-Bit ELF V2 ABI Specification --
OpenPOWER ABI for Linux Supplement" by IBM.
The latter ABI is mainly used on POWER7/7+ and POWER8
Linux systems running in little-endian mode. The code generator
supports both static and dynamic linking. PowerPC 64-bit
code for ELF ABI 1.9 and 2 is mostly position independent
anyway, and thus so is all the code emitted by the code
generator. In other words, -fPIC does not make a difference.

rts/stg/SMP.h support is implemented.

Following the spirit of the introductory comment in
PPC/CodeGen.hs, the rest of the code is a straightforward
extension of the 32-bit implementation.

Limitations:
* Code is generated only in the medium code model, which
  is also gcc's default
* Local symbols are not accessed directly, which seems to
  also be the case for 32-bit
* LLVM does not work, but this does not work on 32-bit either
* Must use the system runtime linker in GHCi, because the
  GHC linker for "static" object files (rts/Linker.c) for
  PPC 64-bit is not implemented. The system runtime
  (dynamic) linker works.
* The handling of the system stack (register 1) is not ELF-
  compliant so stack traces break. Instead of allocating a new
  stack frame, spill code should use the "official" spill area
  in the current stack frame and deallocation code should restore
  the back chain
* DWARF support is missing

Fixes #9863

Test Plan: validate (on powerpc, too)

Reviewers: simonmar, trofi, erikd, austin

Reviewed By: trofi

Subscribers: bgamari, arnons1, kgardas, thomie

Differential Revision: https://phabricator.haskell.org/D629

GHC Trac Issues: #9863

3 files changed, 126 insertions, 1 deletions

diff --git a/rts/StgCRun.c b/rts/StgCRun.c
index 02ec532d4b..29039117ad 100644
--- a/rts/StgCRun.c
+++ b/rts/StgCRun.c
@@ -662,11 +662,19 @@ StgRunIsImplementedInAssembler(void)
 }
 
 #else // linux_HOST_OS
-#error Only linux support for power64 right now.
+#error Only Linux support for power64 right now.
 #endif
 
 #endif
 
+#ifdef powerpc64le_HOST_ARCH
+/* -----------------------------------------------------------------------------
+   PowerPC 64 little endian architecture
+
+   Really everything is in assembler, so we don't have to deal with GCC...
+   -------------------------------------------------------------------------- */
+#endif
+
 /* -----------------------------------------------------------------------------
    ARM architecture
    -------------------------------------------------------------------------- */
diff --git a/rts/StgCRunAsm.S b/rts/StgCRunAsm.S
new file mode 100644
index 0000000000..bb860ca287
--- /dev/null
+++ b/rts/StgCRunAsm.S
@@ -0,0 +1,114 @@
+#include "ghcconfig.h"
+#include "rts/Constants.h"
+#ifdef powerpc64le_HOST_ARCH
+#ifdef linux_HOST_OS
+#define STACK_FRAME_SIZE RESERVED_C_STACK_BYTES+304
+	.file	"StgCRun.c"
+	.abiversion 2
+	.section	".toc","aw"
+	.section	".text"
+	.align 2
+.globl StgRun
+.hidden StgRun
+.type StgRun,@function
+StgRun:
+.localentry StgRun,.-StgRun
+	mflr 0
+	mr 5, 1
+	std 0, 16(1)
+	stdu 1, -(STACK_FRAME_SIZE)(1)
+	std 2, -296(5)
+	std 14, -288(5)
+	std 15, -280(5)
+	std 16, -272(5)
+	std 17, -264(5)
+	std 18, -256(5)
+	std 19, -248(5)
+	std 20, -240(5)
+	std 21, -232(5)
+	std 22, -224(5)
+	std 23, -216(5)
+	std 24, -208(5)
+	std 25, -200(5)
+	std 26, -192(5)
+	std 27, -184(5)
+	std 28, -176(5)
+	std 29, -168(5)
+	std 30, -160(5)
+	std 31, -152(5)
+	stfd 14, -144(5)
+	stfd 15, -136(5)
+	stfd 16, -128(5)
+	stfd 17, -120(5)
+	stfd 18, -112(5)
+	stfd 19, -104(5)
+	stfd 20, -96(5)
+	stfd 21, -88(5)
+	stfd 22, -80(5)
+	stfd 23, -72(5)
+	stfd 24, -64(5)
+	stfd 25, -56(5)
+	stfd 26, -48(5)
+	stfd 27, -40(5)
+	stfd 28, -32(5)
+	stfd 29, -24(5)
+	stfd 30, -16(5)
+	stfd 31, -8(5)
+	mr 27, 4
+	mtctr 3
+	mr 12, 3
+	bctr
+.globl StgReturn
+.type StgReturn,@function
+StgReturn:
+.localentry StgReturn,.-StgReturn
+	mr 3,14
+	la 5, STACK_FRAME_SIZE(1)
+	ld 2, -296(5)
+	ld 14, -288(5)
+	ld 15, -280(5)
+	ld 16, -272(5)
+	ld 17, -264(5)
+	ld 18, -256(5)
+	ld 19, -248(5)
+	ld 20, -240(5)
+	ld 21, -232(5)
+	ld 22, -224(5)
+	ld 23, -216(5)
+	ld 24, -208(5)
+	ld 25, -200(5)
+	ld 26, -192(5)
+	ld 27, -184(5)
+	ld 28, -176(5)
+	ld 29, -168(5)
+	ld 30, -160(5)
+	ld 31, -152(5)
+	lfd 14, -144(5)
+	lfd 15, -136(5)
+	lfd 16, -128(5)
+	lfd 17, -120(5)
+	lfd 18, -112(5)
+	lfd 19, -104(5)
+	lfd 20, -96(5)
+	lfd 21, -88(5)
+	lfd 22, -80(5)
+	lfd 23, -72(5)
+	lfd 24, -64(5)
+	lfd 25, -56(5)
+	lfd 26, -48(5)
+	lfd 27, -40(5)
+	lfd 28, -32(5)
+	lfd 29, -24(5)
+	lfd 30, -16(5)
+	lfd 31, -8(5)
+	mr 1, 5
+	ld 0, 16(1)
+	mtlr 0
+	blr
+
+	.section	.note.GNU-stack,"",@progbits
+#else // linux_HOST_OS
+#error Only Linux support for power64 little endian right now.
+#endif
+
+#endif
diff --git a/rts/ghc.mk b/rts/ghc.mk
index 7fa36b6f17..797e76ba16 100644
--- a/rts/ghc.mk
+++ b/rts/ghc.mk
@@ -45,6 +45,9 @@ ifneq "$(PORTING_HOST)" "YES"
 ifneq "$(findstring $(TargetArch_CPP), i386 powerpc powerpc64)" ""
 rts_S_SRCS += rts/AdjustorAsm.S
 endif
+ifneq "$(findstring $(TargetArch_CPP), powerpc64le)" ""
+rts_S_SRCS += rts/StgCRunAsm.S
+endif
 endif
 
 ifeq "$(GhcUnregisterised)" "YES"