Reland r368691: "[AIX] Implement LR prolog/epilog save/restore"

Trying again with the code changes (and not just the new test).

Summary:
This patch fixes the offsets of fields in the stack frame linkage save
area for AIX.

Reviewers: sfertile, hubert.reinterpretcast, jasonliu, Xiangling_L, xingxue, ZarkoCA, daltenty

Reviewed By: hubert.reinterpretcast

Subscribers: wuzish, nemanjai, hiraditya, kbarton, MaskRay, jsji, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D64424

Patch by Chris Bowler!

llvm-svn: 368721

lib/Target/PowerPC/PPCFrameLowering.cpp

@@ -47,13 +47,15 @@ static const MCPhysReg VRRegNo[] = {
 };
 
 static unsigned computeReturnSaveOffset(const PPCSubtarget &STI) {
-  if (STI.isDarwinABI())
+  if (STI.isDarwinABI() || STI.isAIXABI())
     return STI.isPPC64() ? 16 : 8;
   // SVR4 ABI:
   return STI.isPPC64() ? 16 : 4;
 }
 
 static unsigned computeTOCSaveOffset(const PPCSubtarget &STI) {
+  if (STI.isAIXABI())
+    return STI.isPPC64() ? 40 : 20;
   return STI.isELFv2ABI() ? 24 : 40;
 }
 
@@ -787,15 +789,18 @@ void PPCFrameLowering::emitPrologue(MachineFunction &MF,
   bool isPPC64 = Subtarget.isPPC64();
   // Get the ABI.
   bool isSVR4ABI = Subtarget.isSVR4ABI();
+  bool isAIXABI = Subtarget.isAIXABI();
   bool isELFv2ABI = Subtarget.isELFv2ABI();
-  assert((Subtarget.isDarwinABI() || isSVR4ABI) &&
-         "Currently only Darwin and SVR4 ABIs are supported for PowerPC.");
+  assert((Subtarget.isDarwinABI() || isSVR4ABI || isAIXABI) &&
+         "Unsupported PPC ABI.");
 
   // Scan the prolog, looking for an UPDATE_VRSAVE instruction.  If we find it,
   // process it.
   if (!isSVR4ABI)
     for (unsigned i = 0; MBBI != MBB.end(); ++i, ++MBBI) {
       if (MBBI->getOpcode() == PPC::UPDATE_VRSAVE) {
+        if (isAIXABI)
+          report_fatal_error("UPDATE_VRSAVE is unexpected on AIX.");
         HandleVRSaveUpdate(*MBBI, TII);
         break;
       }
@@ -914,6 +919,9 @@ void PPCFrameLowering::emitPrologue(MachineFunction &MF,
   assert((isPPC64 || !MustSaveCR) &&
          "Prologue CR saving supported only in 64-bit mode");
 
+  if (MustSaveCR && isAIXABI)
+    report_fatal_error("Prologue CR saving is unimplemented on AIX.");
+
   // Check if we can move the stack update instruction (stdu) down the prologue
   // past the callee saves. Hopefully this will avoid the situation where the
   // saves are waiting for the update on the store with update to complete.
@@ -2434,6 +2442,26 @@ PPCFrameLowering::restoreCalleeSavedRegisters(MachineBasicBlock &MBB,
   return true;
 }
 
+unsigned PPCFrameLowering::getTOCSaveOffset() const {
+  if (Subtarget.isAIXABI())
+    // TOC save/restore is normally handled by the linker.
+    // Indirect calls should hit this limitation.
+    report_fatal_error("TOC save is not implemented on AIX yet.");
+  return TOCSaveOffset;
+}
+
+unsigned PPCFrameLowering::getFramePointerSaveOffset() const {
+  if (Subtarget.isAIXABI())
+    report_fatal_error("FramePointer is not implemented on AIX yet.");
+  return FramePointerSaveOffset;
+}
+
+unsigned PPCFrameLowering::getBasePointerSaveOffset() const {
+  if (Subtarget.isAIXABI())
+    report_fatal_error("BasePointer is not implemented on AIX yet.");
+  return BasePointerSaveOffset;
+}
+
 bool PPCFrameLowering::enableShrinkWrapping(const MachineFunction &MF) const {
   if (MF.getInfo<PPCFunctionInfo>()->shrinkWrapDisabled())
     return false;

lib/Target/PowerPC/PPCFrameLowering.h

@@ -143,15 +143,15 @@ public:
 
   /// getTOCSaveOffset - Return the previous frame offset to save the
   /// TOC register -- 64-bit SVR4 ABI only.
-  unsigned getTOCSaveOffset() const { return TOCSaveOffset; }
+  unsigned getTOCSaveOffset() const;
 
   /// getFramePointerSaveOffset - Return the previous frame offset to save the
   /// frame pointer.
-  unsigned getFramePointerSaveOffset() const { return FramePointerSaveOffset; }
+  unsigned getFramePointerSaveOffset() const;
 
   /// getBasePointerSaveOffset - Return the previous frame offset to save the
   /// base pointer.
-  unsigned getBasePointerSaveOffset() const { return BasePointerSaveOffset; }
+  unsigned getBasePointerSaveOffset() const;
 
   /// getCRSaveOffset - Return the previous frame offset to save the
   /// CR register.

test/CodeGen/PowerPC/aix-lr.ll

@@ -0,0 +1,32 @@
+; RUN: llc -verify-machineinstrs -mtriple powerpc-ibm-aix-xcoff < %s | \
+; RUN: FileCheck --check-prefix=32BIT %s
+
+; RUN: llc -verify-machineinstrs -mtriple powerpc64-ibm-aix-xcoff < %s | \
+; RUN: FileCheck --check-prefix=64BIT %s
+
+define void @bar() {
+entry:
+
+; 32BIT: mflr 0
+; 32BIT: stw 0, 8(1)
+; 32BIT: stwu 1, -64(1)
+; 32BIT: bl .foo
+; 32BIT: nop
+; 32BIT: addi 1, 1, 64
+; 32BIT: lwz 0, 8(1)
+; 32BIT: mtlr 0
+
+; 64BIT: mflr 0
+; 64BIT: std 0, 16(1)
+; 64BIT: stdu 1, -112(1)
+; 64BIT: bl .foo
+; 64BIT: nop
+; 64BIT: addi 1, 1, 112
+; 64BIT: ld 0, 16(1)
+; 64BIT: mtlr 0
+
+  call void bitcast (void (...)* @foo to void ()*)()
+  ret void
+}
+
+declare void @foo(...)

test/CodeGen/PowerPC/test_call_aix.ll

@@ -1,5 +1,3 @@
-; XFAIL: asserts
-
 ; RUN: llc -mtriple powerpc-ibm-aix-xcoff -stop-after=machine-cp < %s | \
 ; RUN: FileCheck --check-prefix=32BIT %s