[SystemZ] Emit optional argument area length field

llvm/lib/Target/SystemZ/SystemZAsmPrinter.cpp

@@ -1270,7 +1270,7 @@ void SystemZAsmPrinter::emitFunctionBodyEnd() {
 
 static void emitPPA1Flags(std::unique_ptr<MCStreamer> &OutStreamer, bool VarArg,
                           bool StackProtector, bool FPRMask, bool VRMask,
-                          bool EHBlock, bool HasName) {
+                          bool EHBlock, bool HasArgAreaLength, bool HasName) {
   enum class PPA1Flag1 : uint8_t {
     DSA64Bit = (0x80 >> 0),
     VarArg = (0x80 >> 7),
@@ -1282,8 +1282,9 @@ static void emitPPA1Flags(std::unique_ptr<MCStreamer> &OutStreamer, bool VarArg,
     LLVM_MARK_AS_BITMASK_ENUM(ExternalProcedure)
   };
   enum class PPA1Flag3 : uint8_t {
+    HasArgAreaLength = (0x80 >> 1),
     FPRMask = (0x80 >> 2),
-    LLVM_MARK_AS_BITMASK_ENUM(FPRMask)
+    LLVM_MARK_AS_BITMASK_ENUM(HasArgAreaLength)
   };
   enum class PPA1Flag4 : uint8_t {
     EPMOffsetPresent = (0x80 >> 0),
@@ -1307,6 +1308,9 @@ static void emitPPA1Flags(std::unique_ptr<MCStreamer> &OutStreamer, bool VarArg,
   if (StackProtector)
     Flags2 |= PPA1Flag2::STACKPROTECTOR;
 
+  if (HasArgAreaLength)
+    Flags3 |= PPA1Flag3::HasArgAreaLength; // Add emit ArgAreaLength flag.
+
   // SavedGPRMask, SavedFPRMask, and SavedVRMask are precomputed in.
   if (FPRMask)
     Flags3 |= PPA1Flag3::FPRMask; // Add emit FPR mask flag.
@@ -1339,6 +1343,9 @@ static void emitPPA1Flags(std::unique_ptr<MCStreamer> &OutStreamer, bool VarArg,
   OutStreamer->emitInt8(static_cast<uint8_t>(Flags2)); // Flags 2.
 
   OutStreamer->AddComment("PPA1 Flags 3");
+  if ((Flags3 & PPA1Flag3::HasArgAreaLength) == PPA1Flag3::HasArgAreaLength)
+    OutStreamer->AddComment(
+        "  Bit 1: 1 = Argument Area Length is in optional area");
   if ((Flags3 & PPA1Flag3::FPRMask) == PPA1Flag3::FPRMask)
     OutStreamer->AddComment("  Bit 2: 1 = FP Reg Mask is in optional area");
   OutStreamer->emitInt8(
@@ -1477,19 +1484,38 @@ void SystemZAsmPrinter::emitPPA1(MCSymbol *FnEndSym) {
 
   bool NeedEmitEHBlock = !MF->getLandingPads().empty();
 
+  // Optional Argument Area Length.
+  // Note: This represents the length of the argument area that we reserve
+  //       in our stack for setting up arguments for calls to other
+  //       routines. If this optional field is not set, LE will reserve
+  //       128 bytes for the argument area. This optional field is
+  //       created if greater than 128 bytes is required - to guarantee
+  //       the required space is reserved on stack extension in the new
+  //       extension.  This optional field is also created if the
+  //       routine has alloca(). This may reduce stack space
+  //       if alloca() call causes a stack extension.
+  bool HasArgAreaLength =
+      (AllocaReg != 0) || (MFFrame.getMaxCallFrameSize() > 128);
+
   bool HasName =
       MF->getFunction().hasName() && MF->getFunction().getName().size() > 0;
 
   emitPPA1Flags(OutStreamer, MF->getFunction().isVarArg(),
                 MFFrame.hasStackProtectorIndex(), SavedFPRMask != 0,
-                TargetHasVector && SavedVRMask != 0, NeedEmitEHBlock, HasName);
+                TargetHasVector && SavedVRMask != 0, NeedEmitEHBlock,
+                HasArgAreaLength, HasName);
 
   OutStreamer->AddComment("Length/4 of Parms");
   OutStreamer->emitInt16(
       static_cast<uint16_t>(ZFI->getSizeOfFnParams() / 4)); // Parms/4.
   OutStreamer->AddComment("Length of Code");
   OutStreamer->emitAbsoluteSymbolDiff(FnEndSym, CurrentFnEPMarkerSym, 4);
 
+  if (HasArgAreaLength) {
+    OutStreamer->AddComment("Argument Area Length");
+    OutStreamer->emitInt32(MFFrame.getMaxCallFrameSize());
+  }
+
   // Emit saved FPR mask and offset to FPR save area (0x20 of flags 3).
   if (SavedFPRMask) {
     OutStreamer->AddComment("FPR mask");

llvm/test/CodeGen/SystemZ/zos-ppa1-argarea.ll

@@ -0,0 +1,66 @@
+; RUN: llc < %s -mtriple=s390x-ibm-zos -emit-gnuas-syntax-on-zos=0 | FileCheck %s
+%struct.LargeStruct_t = type { [33 x i32] }
+
+@GlobLargeS = hidden global %struct.LargeStruct_t zeroinitializer, align 4
+@GlobInt = hidden global i32 0, align 4
+
+; === Check that function with small frame does not emit PPA1 Argument Area Length.
+define void @fSmallOutArgArea() {
+; CHECK-LABEL: L#EPM_fSmallOutArgArea_0 DS 0H
+; CHECK: *   Bit 1: 1 = Leaf function
+; CHECK: *   Bit 2: 0 = Does not use alloca
+; CHECK:  DC XL4'00000008'
+; CHECK: fSmallOutArgArea DS 0H
+; CHECK: L#PPA1_fSmallOutArgArea_0 DS 0H
+; CHECK: * PPA1 Flags 3
+; CHECK:  DC XL1'00'
+  ret void
+}
+
+; === Check that function with large frame does emit PPA1 Argument Area Length.
+define void @fLargeOutArgArea() {
+; CHECK-LABEL: L#EPM_fLargeOutArgArea_0 DS 0H
+; CHECK: *   Bit 1: 0 = Non-leaf function
+; CHECK: *   Bit 2: 0 = Does not use alloca
+; CHECK:  DC XL4'00000220'
+; CHECK: fLargeOutArgArea DS 0H
+; CHECK: L#PPA1_fLargeOutArgArea_0 DS 0H
+; CHECK: * PPA1 Flags 3
+; CHECK: *   Bit 1: 1 = Argument Area Length is in optional area
+; CHECK:  DC XL1'40'
+; CHECK: * Argument Area Length
+; CHECK:  DC XL4'00000140'
+  %1 = load [33 x i32], ptr @GlobLargeS, align 4
+  call void @fLargeParm([33 x i32] inreg %1)
+  ret void
+}
+
+; === Check that function with parameter does emit PPA1 Length/4 of parms
+define void @fLargeParm([33 x i64] inreg %arr) {
+; CHECK-LABEL: L#EPM_fLargeParm_0 DS 0H
+; CHECK: * Length/4 of Parms
+; CHECK:  DC XL2'0042'
+  %1 = extractvalue [33 x i64] %arr, 1
+  call void @foo(i64 %1)
+  ret void
+}
+
+; === Check that function with alloca call does emit PPA1 Argument Area Length.
+define hidden void @fHasAlloca() {
+; CHECK-LABEL: L#EPM_fHasAlloca_0 DS 0H
+; CHECK: *   Bit 2: 1 = Uses alloca
+; CHECK: fHasAlloca DS 0H
+; CHECK: L#PPA1_fHasAlloca_0 DS 0H
+; CHECK: * PPA1 Flags 3
+; CHECK: *   Bit 1: 1 = Argument Area Length is in optional area
+; CHECK:  DC XL1'40'
+; CHECK: * Argument Area Length
+; CHECK:  DC XL4'00000040'
+  %p = alloca ptr, align 4
+  %1 = load i32, ptr @GlobInt, align 4
+  %2 = alloca i8, i32 %1, align 8
+  store ptr %2, ptr %p, align 4
+  ret void
+}
+
+declare void @foo(i64)