[AIX] Support init priority

[Xiangling_L]

Summary

Support reserved [0-100] and non-reserved[101-65535] Clang/GNU init priority values on AIX.

This patch maps Clang/GNU values into priority values used in sinit/sterm functions. User can play with values and be able to get init to occur before or after XL init and vice versa.

The conversion strategies are: For [0-100] reserved and [101-65535] non-reserved Clang/GNU values, we use linear interpolation to map Clang to sinit/sterm priority values. But 21/20 on reserved range ends and 1024 on both non-reserved range ends will be used with a factor of 1.

[Xiangling_L]

Fix wrong sinit/sterm function formatting issue;

[sfertile]

llvm/lib/Target/PowerPC/PPCAsmPrinter.cpp

2003

The comment and table do a good job explains the mapping you want to do, but could we condense it without loosing too much if we reworded it? Something along the lines of:

We map the reserved clang/gnu priority range [0-100] into the sterm/sinit reserved priority range [0,1023] by 
- directly mapping the first 20 elements of the ranges
- directly mapping the last 20 elements of the ranges
- linear interpolating the intermediate values with a step size of 16.

We map the non reserved clang/gnu priority range of [101, 65535] into the sterm/sinit priority range [1024,2147483648] by:
- directly mapping the first 1023 elements of the ranges
- directly mapping the last 1023 elements of the ranges.
- linear interpolating the intermediate values with a step size of 33878.

2037

Suggestion: Having the actual mapping done in a separate helper cleans up the initialization:

unsigned MapedPriority = mapPriorityToSinit(Priority);

llvm/test/CodeGen/PowerPC/aix-static-init-non-default-priority.ll

1–2

missing -verify-machineinstrs

[Xiangling_L]

Addressed the comments;

[sfertile]

A couple of really minor comments, but otherwise LGTM.

llvm/lib/Target/PowerPC/PPCAsmPrinter.cpp

2000

Its simpler if we use returns:

if (P <=20)
  return P;

if (P < 81)
  return 20 + (P - 20) * 16;

etc ...

2028

Real minor nit: Move this inside the helper function.

[Xiangling_L]

Addressed comments;

[sfertile]

LGTM.

llvm/lib/Target/PowerPC/PPCAsmPrinter.cpp

 }
 
 bool PPCAIXAsmPrinter::doFinalization(Module &M) {
   for (MCSymbol *Sym : ExtSymSDNodeSymbols)
     OutStreamer->emitSymbolAttribute(Sym, MCSA_Extern);
   return PPCAsmPrinter::doFinalization(M);
 }
 
+static unsigned mapToSinitPriority(unsigned P) {
+  if (P > 20 && P < 81) {
+    P = 20 + (P - 20) * 16;
+  } else if (P >= 81 && P <= 1124) {
+    P = 1004 + (P - 81);
+  } else if (P > 1124 && P < 64512) {
+    P = 2047 + (P - 1124) * 33878;
+  } else if (P >= 64512 && P <= 65535) {
+    P = 2147482625 + (P - 64512);
+  }
+
+  return P;
+}
+
+static std::string convertToSinitPriority(int Priority) {
+  // This helper function converts clang init priority to values used in sinit
+  // and sterm functions.
+  //
+  // The conversion strategies are:
+  // We map the reserved clang/gnu priority range [0, 100] into the sinit/sterm
+  // reserved priority range [0, 1023] by
+  // - directly mapping the first 21 and the last 20 elements of the ranges
+  // - linear interpolating the intermediate values with a step size of 16.
+  //
+  // We map the non reserved clang/gnu priority range of [101, 65535] into the
+  // sinit/sterm priority range [1024, 2147483648] by:
+  // - directly mapping the first and the last 1024 elements of the ranges
+  // - linear interpolating the intermediate values with a step size of 33878.
+
+  if (Priority < 0 || Priority > 65535)
+    report_fatal_error("invalid init priority");
+
+  unsigned int P = mapToSinitPriority(Priority);
+
+  std::string PrioritySuffix;
+  llvm::raw_string_ostream os(PrioritySuffix);
+  os << llvm::format_hex_no_prefix(P, 8);
+  os.flush();
+  return PrioritySuffix;
+}
+
 void PPCAIXAsmPrinter::emitXXStructorList(const DataLayout &DL,
                                           const Constant *List, bool IsCtor) {
   SmallVector<Structor, 8> Structors;
   preprocessXXStructorList(DL, List, Structors);
   if (Structors.empty())
     return;
 
   unsigned Index = 0;
   for (Structor &S : Structors) {
-    if (S.Priority != 65535)
-      report_fatal_error(
-          "prioritized sinit and sterm functions are not yet supported on AIX");
+    if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(S.Func))
+      S.Func = CE->getOperand(0);
 
     llvm::GlobalAlias::create(
         GlobalValue::ExternalLinkage,
         (IsCtor ? llvm::Twine("__sinit") : llvm::Twine("__sterm")) +
-            llvm::Twine("80000000_", FormatIndicatorAndUniqueModId) +
+            llvm::Twine(convertToSinitPriority(S.Priority)) +
+            llvm::Twine("_", FormatIndicatorAndUniqueModId) +
             llvm::Twine("_", llvm::utostr(Index++)),
         cast<Function>(S.Func));
   }
 }
 
 /// createPPCAsmPrinterPass - Returns a pass that prints the PPC assembly code
 /// for a MachineFunction to the given output stream, in a format that the
 /// Darwin assembler can deal with.

llvm/test/CodeGen/PowerPC/aix-static-init-non-default-priority.ll

-; RUN: not --crash llc -mtriple powerpc-ibm-aix-xcoff < %s 2>&1 | FileCheck %s
-; RUN: not --crash llc -mtriple powerpc64-ibm-aix-xcoff < %s 2>&1 | FileCheck %s
+; RUN: llc -mtriple powerpc-ibm-aix-xcoff -verify-machineinstrs < %s | FileCheck %s
+; RUN: llc -mtriple powerpc64-ibm-aix-xcoff -verify-machineinstrs < %s | FileCheck %s
 
[e-mail]_ctors = appending global [1 x { i32, void ()*, i8* }] [{ i32, void ()*, i8* } { i32 655, void ()* @foo, i8* null }]
[e-mail]_ctors = appending global [5 x { i32, void ()*, i8* }] [{ i32, void ()*, i8* } { i32 0, void ()* bitcast (i32 (i32)* @cf1 to void ()*), i8* null }, { i32, void ()*, i8* } { i32 21, void ()* @cf2, i8* null }, { i32, void ()*, i8* } { i32 81, void ()* @cf3, i8* null }, { i32, void ()*, i8* } { i32 1125, void ()* @cf4, i8* null }, { i32, void ()*, i8* } { i32 64512, void ()* @cf5, i8* null }]
[e-mail]_dtors = appending global [5 x { i32, void ()*, i8* }] [{ i32, void ()*, i8* } { i32 20, void ()* bitcast (i32 (i32)* @df1 to void ()*), i8* null }, { i32, void ()*, i8* } { i32 80, void ()* @df2, i8* null }, { i32, void ()*, i8* } { i32 1124, void ()* @df3, i8* null }, { i32, void ()*, i8* } { i32 64511, void ()* @df4, i8* null }, { i32, void ()*, i8* } { i32 65535, void ()* @df5, i8* null }]
 
-define void @foo() {
+define i32 @cf1(i32 %a) {
+  ret i32 %a
+}
+
+define void @cf2() {
+  ret void
+}
+
+define void @cf3() {
+  ret void
+}
+
+define void @cf4() {
+  ret void
+}
+
+define void @cf5() {
   ret void
 }
 
-; CHECK: LLVM ERROR: prioritized sinit and sterm functions are not yet supported
+define i32 @df1(i32 %a) {
+  ret i32 %a
+}
+
+define void @df2() {
+  ret void
+}
+
+define void @df3() {
+  ret void
+}
+
+define void @df4() {
+  ret void
+}
+
+define void @df5() {
+  ret void
+}
+
+; CHECK:   .globl  cf1[DS]
+; CHECK:   .globl  .cf1
+; CHECK:   .align  2
+; CHECK:   .csect cf1[DS]
+; CHECK: __sinit00000000_clang_f6a1bc9396775a64c6249effda300afe_0: # @cf1
+; CHECK: .cf1:
+; CHECK: .__sinit00000000_clang_f6a1bc9396775a64c6249effda300afe_0:
+
+; CHECK:   .globl  cf2[DS]
+; CHECK:   .globl  .cf2
+; CHECK:   .align  2
+; CHECK:   .csect cf2[DS]
+; CHECK: __sinit00000024_clang_f6a1bc9396775a64c6249effda300afe_1: # @cf2
+; CHECK: .cf2:
+; CHECK: .__sinit00000024_clang_f6a1bc9396775a64c6249effda300afe_1:
+
+; CHECK:   .globl  cf3[DS]
+; CHECK:   .globl  .cf3
+; CHECK:   .align  2
+; CHECK:   .csect cf3[DS]
+; CHECK: __sinit000003ec_clang_f6a1bc9396775a64c6249effda300afe_2: # @cf3
+; CHECK: .cf3:
+; CHECK: .__sinit000003ec_clang_f6a1bc9396775a64c6249effda300afe_2:
+
+; CHECK:   .globl  cf4[DS]
+; CHECK:   .globl  .cf4
+; CHECK:   .align  2
+; CHECK:   .csect cf4[DS]
+; CHECK: __sinit00008c55_clang_f6a1bc9396775a64c6249effda300afe_3: # @cf4
+; CHECK: .cf4:
+; CHECK: .__sinit00008c55_clang_f6a1bc9396775a64c6249effda300afe_3:
+
+; CHECK:   .globl  cf5[DS]
+; CHECK:   .globl  .cf5
+; CHECK:   .align  2
+; CHECK:   .csect cf5[DS]
+; CHECK: __sinit7ffffc01_clang_f6a1bc9396775a64c6249effda300afe_4: # @cf5
+; CHECK: .cf5:
+; CHECK: .__sinit7ffffc01_clang_f6a1bc9396775a64c6249effda300afe_4:
+
+; CHECK:   .globl  df1[DS]
+; CHECK:   .globl  .df1
+; CHECK:   .align  2
+; CHECK:   .csect df1[DS]
+; CHECK: __sterm00000014_clang_f6a1bc9396775a64c6249effda300afe_0: # @df1
+; CHECK: .df1:
+; CHECK: .__sterm00000014_clang_f6a1bc9396775a64c6249effda300afe_0:
+
+; CHECK:   .globl  df2[DS]
+; CHECK:   .globl  .df2
+; CHECK:   .align  2
+; CHECK:   .csect df2[DS]
+; CHECK: __sterm000003d4_clang_f6a1bc9396775a64c6249effda300afe_1: # @df2
+; CHECK: .df2:
+; CHECK: .__sterm000003d4_clang_f6a1bc9396775a64c6249effda300afe_1:
+
+; CHECK:   .globl  df3[DS]
+; CHECK:   .globl  .df3
+; CHECK:   .align  2
+; CHECK:   .csect df3[DS]
+; CHECK: __sterm000007ff_clang_f6a1bc9396775a64c6249effda300afe_2: # @df3
+; CHECK: .df3:
+; CHECK: .__sterm000007ff_clang_f6a1bc9396775a64c6249effda300afe_2:
+
+; CHECK:   .globl  df4[DS]
+; CHECK:   .globl  .df4
+; CHECK:   .align  2
+; CHECK:   .csect df4[DS]
+; CHECK: __sterm7fff2211_clang_f6a1bc9396775a64c6249effda300afe_3: # @df4
+; CHECK: .df4:
+; CHECK: .__sterm7fff2211_clang_f6a1bc9396775a64c6249effda300afe_3:
+
+; CHECK:   .globl  df5[DS]
+; CHECK:   .globl  .df5
+; CHECK:   .align  2
+; CHECK:   .csect df5[DS]
+; CHECK: __sterm80000000_clang_f6a1bc9396775a64c6249effda300afe_4: # @df5
+; CHECK: .df5:
+; CHECK: .__sterm80000000_clang_f6a1bc9396775a64c6249effda300afe_4:
+
+; CHECK:   .globl  __sinit00000000_clang_f6a1bc9396775a64c6249effda300afe_0
+; CHECK:   .globl  .__sinit00000000_clang_f6a1bc9396775a64c6249effda300afe_0
+; CHECK:   .globl  __sinit00000024_clang_f6a1bc9396775a64c6249effda300afe_1
+; CHECK:   .globl  .__sinit00000024_clang_f6a1bc9396775a64c6249effda300afe_1
+; CHECK:   .globl  __sinit000003ec_clang_f6a1bc9396775a64c6249effda300afe_2
+; CHECK:   .globl  .__sinit000003ec_clang_f6a1bc9396775a64c6249effda300afe_2
+; CHECK:   .globl  __sinit00008c55_clang_f6a1bc9396775a64c6249effda300afe_3
+; CHECK:   .globl  .__sinit00008c55_clang_f6a1bc9396775a64c6249effda300afe_3
+; CHECK:   .globl  __sinit7ffffc01_clang_f6a1bc9396775a64c6249effda300afe_4
+; CHECK:   .globl  .__sinit7ffffc01_clang_f6a1bc9396775a64c6249effda300afe_4
+; CHECK:   .globl  __sterm00000014_clang_f6a1bc9396775a64c6249effda300afe_0
+; CHECK:   .globl  .__sterm00000014_clang_f6a1bc9396775a64c6249effda300afe_0
+; CHECK:   .globl  __sterm000003d4_clang_f6a1bc9396775a64c6249effda300afe_1
+; CHECK:   .globl  .__sterm000003d4_clang_f6a1bc9396775a64c6249effda300afe_1
+; CHECK:   .globl  __sterm000007ff_clang_f6a1bc9396775a64c6249effda300afe_2
+; CHECK:   .globl  .__sterm000007ff_clang_f6a1bc9396775a64c6249effda300afe_2
+; CHECK:   .globl  __sterm7fff2211_clang_f6a1bc9396775a64c6249effda300afe_3
+; CHECK:   .globl  .__sterm7fff2211_clang_f6a1bc9396775a64c6249effda300afe_3
+; CHECK:   .globl  __sterm80000000_clang_f6a1bc9396775a64c6249effda300afe_4
+; CHECK:   .globl  .__sterm80000000_clang_f6a1bc9396775a64c6249effda300afe_4