[AsmPrinterDwarf] Add support for .cfi_restore directive

As of today we only use .cfi_offset to specify the offset of a CSR, but we never use .cfi_restore when the CSR is restored. If we want to perform a more advanced type of shrink-wrapping, we need to use .cfi_restore in order to switch the CFI state between blocks. This patch only aims at adding support for the directive. Differential Revision: https://reviews.llvm.org/D36114 llvm-svn: 317199
llvm · Nov 2, 2017 · 66d2c26 · 66d2c26
1 parent e73b85d
commit 66d2c26
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Showing 10 changed files with 148 additions and 31 deletions.
diff --git a/llvm/lib/CodeGen/AsmPrinter/AsmPrinterDwarf.cpp b/llvm/lib/CodeGen/AsmPrinter/AsmPrinterDwarf.cpp
@@ -219,6 +219,9 @@ void AsmPrinter::emitCFIInstruction(const MCCFIInstruction &Inst) const {
   case MCCFIInstruction::OpEscape:
     OutStreamer->EmitCFIEscape(Inst.getValues());
     break;
+  case MCCFIInstruction::OpRestore:
+    OutStreamer->EmitCFIRestore(Inst.getRegister());
+    break;
   }
 }
 

diff --git a/llvm/lib/CodeGen/MIRParser/MILexer.cpp b/llvm/lib/CodeGen/MIRParser/MILexer.cpp
@@ -216,6 +216,7 @@ static MIToken::TokenKind getIdentifierKind(StringRef Identifier) {
       .Case("def_cfa_register", MIToken::kw_cfi_def_cfa_register)
       .Case("def_cfa_offset", MIToken::kw_cfi_def_cfa_offset)
       .Case("def_cfa", MIToken::kw_cfi_def_cfa)
+      .Case("restore", MIToken::kw_cfi_restore)
       .Case("blockaddress", MIToken::kw_blockaddress)
       .Case("intrinsic", MIToken::kw_intrinsic)
       .Case("target-index", MIToken::kw_target_index)

diff --git a/llvm/lib/CodeGen/MIRParser/MILexer.h b/llvm/lib/CodeGen/MIRParser/MILexer.h
@@ -68,6 +68,7 @@ struct MIToken {
     kw_cfi_def_cfa_register,
     kw_cfi_def_cfa_offset,
     kw_cfi_def_cfa,
+    kw_cfi_restore,
     kw_blockaddress,
     kw_intrinsic,
     kw_target_index,

diff --git a/llvm/lib/CodeGen/MIRParser/MIParser.cpp b/llvm/lib/CodeGen/MIRParser/MIParser.cpp
@@ -1634,6 +1634,12 @@ bool MIParser::parseCFIOperand(MachineOperand &Dest) {
     CFIIndex =
         MF.addFrameInst(MCCFIInstruction::createDefCfa(nullptr, Reg, -Offset));
     break;
+  case MIToken::kw_cfi_restore:
+    if (parseCFIRegister(Reg))
+      return true;
+    CFIIndex = MF.addFrameInst(MCCFIInstruction::createRestore(nullptr, Reg));
+    break;
+
   default:
     // TODO: Parse the other CFI operands.
     llvm_unreachable("The current token should be a cfi operand");
@@ -1912,6 +1918,7 @@ bool MIParser::parseMachineOperand(MachineOperand &Dest,
   case MIToken::kw_cfi_def_cfa_register:
   case MIToken::kw_cfi_def_cfa_offset:
   case MIToken::kw_cfi_def_cfa:
+  case MIToken::kw_cfi_restore:
     return parseCFIOperand(Dest);
   case MIToken::kw_blockaddress:
     return parseBlockAddressOperand(Dest);

diff --git a/llvm/lib/CodeGen/MIRPrinter.cpp b/llvm/lib/CodeGen/MIRPrinter.cpp
@@ -1243,6 +1243,12 @@ void MIPrinter::print(const MCCFIInstruction &CFI,
     printCFIRegister(CFI.getRegister(), OS, TRI);
     OS << ", " << CFI.getOffset();
     break;
+  case MCCFIInstruction::OpRestore:
+    OS << "restore ";
+    if (CFI.getLabel())
+      OS << "<mcsymbol> ";
+    printCFIRegister(CFI.getRegister(), OS, TRI);
+    break;
   default:
     // TODO: Print the other CFI Operations.
     OS << "<unserializable cfi operation>";

diff --git a/llvm/lib/MC/MCAsmStreamer.cpp b/llvm/lib/MC/MCAsmStreamer.cpp
@@ -260,6 +260,7 @@ class MCAsmStreamer final : public MCStreamer {
   void EmitCFILsda(const MCSymbol *Sym, unsigned Encoding) override;
   void EmitCFIRememberState() override;
   void EmitCFIRestoreState() override;
+  void EmitCFIRestore(int64_t Register) override;
   void EmitCFISameValue(int64_t Register) override;
   void EmitCFIRelOffset(int64_t Register, int64_t Offset) override;
   void EmitCFIAdjustCfaOffset(int64_t Adjustment) override;
@@ -1385,6 +1386,13 @@ void MCAsmStreamer::EmitCFIRestoreState() {
   EmitEOL();
 }
 
+void MCAsmStreamer::EmitCFIRestore(int64_t Register) {
+  MCStreamer::EmitCFIRestore(Register);
+  OS << "\t.cfi_restore ";
+  EmitRegisterName(Register);
+  EmitEOL();
+}
+
 void MCAsmStreamer::EmitCFISameValue(int64_t Register) {
   MCStreamer::EmitCFISameValue(Register);
   OS << "\t.cfi_same_value ";

diff --git a/llvm/test/CodeGen/AArch64/cfi_restore.mir b/llvm/test/CodeGen/AArch64/cfi_restore.mir
@@ -0,0 +1,37 @@
+# RUN: llc -mtriple=aarch64-- -start-after prologepilog -o - %s | FileCheck %s
+---
+name:            fun
+# CHECK: .cfi_startproc
+tracksRegLiveness: true
+frameInfo:
+  stackSize:       16
+  maxAlignment:    8
+  hasCalls:        true
+stack:
+  - { id: 0, type: spill-slot, offset: -8, size: 8, alignment: 8, stack-id: 0,
+      callee-saved-register: '%lr' }
+  - { id: 1, type: spill-slot, offset: -16, size: 8, alignment: 8, stack-id: 0,
+      callee-saved-register: '%fp' }
+body:             |
+  bb.0:
+    liveins: %fp, %lr
+
+    %sp = frame-setup SUBXri %sp, 16, 0
+    frame-setup STRXui killed %fp, %sp, 0 :: (store 8 into %stack.1)
+    frame-setup CFI_INSTRUCTION offset %w29, -16
+    ; CHECK: .cfi_offset w29, -16
+    frame-setup STRXui killed %lr, %sp, 1 :: (store 8 into %stack.0)
+    frame-setup CFI_INSTRUCTION offset %w30, -8
+    ; CHECK: .cfi_offset w30, -8
+    %fp = frame-setup ADDXri %sp, 0, 0
+    frame-setup CFI_INSTRUCTION def_cfa %w29, 16
+    %lr = LDRXui %sp, 1 :: (load 8 from %stack.0)
+    CFI_INSTRUCTION restore %w30
+    ; CHECK: .cfi_restore w30
+    %fp = LDRXui %sp, 0 :: (load 8 from %stack.1)
+    CFI_INSTRUCTION restore %w29
+    ; CHECK: .cfi_restore w29
+    %sp = ADDXri %sp, 16, 0
+    RET_ReallyLR
+    ; CHECK: .cfi_endproc
+...
diff --git a/llvm/test/CodeGen/MIR/AArch64/cfi-def-cfa.mir b/llvm/test/CodeGen/MIR/AArch64/cfi-def-cfa.mir
diff --git a/llvm/test/CodeGen/MIR/AArch64/cfi.mir b/llvm/test/CodeGen/MIR/AArch64/cfi.mir
@@ -0,0 +1,59 @@
+# RUN: llc -mtriple=aarch64-none-linux-gnu -run-pass none -o - %s | FileCheck %s
+# This test ensures that the MIR parser parses the cfi directives correctly.
+
+--- |
+
+  declare void @foo()
+
+  define void @trivial_fp_func() {
+  entry:
+    call void @foo()
+    ret void
+  }
+
+  define void @trivial_fp_func_restore() {
+  entry:
+    call void @foo()
+    ret void
+  }
+
+...
+---
+name:            trivial_fp_func
+# CHECK-LABEL: name: trivial_fp_func
+body: |
+  bb.0.entry:
+    liveins: %lr, %fp, %lr, %fp
+
+    %sp = frame-setup STPXpre killed %fp, killed %lr, %sp, -2
+    %fp = frame-setup ADDXri %sp, 0, 0
+    ; CHECK: CFI_INSTRUCTION def_cfa %w29, 16
+    frame-setup CFI_INSTRUCTION def_cfa %w29, 16
+    frame-setup CFI_INSTRUCTION offset %w30, -8
+    frame-setup CFI_INSTRUCTION offset %w29, -16
+    BL @foo, csr_aarch64_aapcs, implicit-def dead %lr, implicit %sp, implicit-def %sp
+    %sp, %fp, %lr = LDPXpost %sp, 2
+    RET_ReallyLR
+...
+---
+name:            trivial_fp_func_restore
+# CHECK-LABEL: name: trivial_fp_func_restore
+body: |
+  bb.0.entry:
+    liveins: %lr, %fp
+
+    %sp = frame-setup STPXpre killed %fp, killed %lr, %sp, -2
+    %fp = frame-setup ADDXri %sp, 0, 0
+    frame-setup CFI_INSTRUCTION def_cfa %w29, 16
+    frame-setup CFI_INSTRUCTION offset %w30, -8
+    ; CHECK: CFI_INSTRUCTION offset %w30, -8
+    frame-setup CFI_INSTRUCTION offset %w29, -16
+    ; CHECK: CFI_INSTRUCTION offset %w29, -16
+    BL @foo, csr_aarch64_aapcs, implicit-def dead %lr, implicit %sp, implicit-def %sp
+    %sp, %fp, %lr = LDPXpost %sp, 2
+    CFI_INSTRUCTION restore %w30
+    ; CHECK: CFI_INSTRUCTION restore %w30
+    CFI_INSTRUCTION restore %w29
+    ; CHECK: CFI_INSTRUCTION restore %w29
+    RET_ReallyLR
+...
diff --git a/llvm/test/MC/AArch64/cfi.s b/llvm/test/MC/AArch64/cfi.s
@@ -0,0 +1,26 @@
+// RUN: llvm-mc -triple aarch64-- -o - %s | FileCheck %s
+
+fun:
+  .cfi_startproc
+// CHECK: .cfi_startproc
+  stp  x29, x30, [sp, #-16]!
+.Lcfi0:
+  .cfi_offset w29, -16
+// CHECK: .cfi_offset w29, -16
+.Lcfi1:
+  .cfi_offset w30, -8
+// CHECK: .cfi_offset w30, -8
+  mov   x29, sp
+.Lcfi2:
+  .cfi_def_cfa w29, 16
+// CHECK: .cfi_def_cfa w29, 16
+.Lcfi3:
+  .cfi_restore w30
+// CHECK: .cfi_restore w30
+  ldr  x29, [sp], #16
+.Lcfi4:
+  .cfi_restore w29
+// CHECK: .cfi_restore w29
+  ret
+  .cfi_endproc
+// CHECK: .cfi_endproc