[AVR] Implement TargetLoweing::getRegisterByName

This allows the use of the 'read_register' intrinsics used by clang's
named register globals features.

llvm-svn: 291375

3 files changed, 61 insertions, 0 deletions

diff --git a/llvm/lib/Target/AVR/AVRISelLowering.cpp b/llvm/lib/Target/AVR/AVRISelLowering.cpp
index 53668f05b59..07fc3f6890b 100644
--- a/llvm/lib/Target/AVR/AVRISelLowering.cpp
+++ b/llvm/lib/Target/AVR/AVRISelLowering.cpp
@@ -14,6 +14,7 @@
 
 #include "AVRISelLowering.h"
 
+#include "llvm/ADT/StringSwitch.h"
 #include "llvm/CodeGen/CallingConvLower.h"
 #include "llvm/CodeGen/MachineFrameInfo.h"
 #include "llvm/CodeGen/MachineInstrBuilder.h"
@@ -1933,5 +1934,45 @@ void AVRTargetLowering::LowerAsmOperandForConstraint(SDValue Op,
   return TargetLowering::LowerAsmOperandForConstraint(Op, Constraint, Ops, DAG);
 }
 
+unsigned AVRTargetLowering::getRegisterByName(const char *RegName,
+                                              EVT VT,
+                                              SelectionDAG &DAG) const {
+  unsigned Reg;
+
+  if (VT == MVT::i8) {
+    Reg = StringSwitch<unsigned>(RegName)
+      .Case("r0", AVR::R0).Case("r1", AVR::R1).Case("r2", AVR::R2)
+      .Case("r3", AVR::R3).Case("r4", AVR::R4).Case("r5", AVR::R5)
+      .Case("r6", AVR::R6).Case("r7", AVR::R7).Case("r8", AVR::R8)
+      .Case("r9", AVR::R9).Case("r10", AVR::R10).Case("r11", AVR::R11)
+      .Case("r12", AVR::R12).Case("r13", AVR::R13).Case("r14", AVR::R14)
+      .Case("r15", AVR::R15).Case("r16", AVR::R16).Case("r17", AVR::R17)
+      .Case("r18", AVR::R18).Case("r19", AVR::R19).Case("r20", AVR::R20)
+      .Case("r21", AVR::R21).Case("r22", AVR::R22).Case("r23", AVR::R23)
+      .Case("r24", AVR::R24).Case("r25", AVR::R25).Case("r26", AVR::R26)
+      .Case("r27", AVR::R27).Case("r28", AVR::R28).Case("r29", AVR::R29)
+      .Case("r30", AVR::R30).Case("r31", AVR::R31)
+      .Case("X", AVR::R27R26).Case("Y", AVR::R29R28).Case("Z", AVR::R31R30)
+      .Default(0);
+  } else {
+    Reg = StringSwitch<unsigned>(RegName)
+      .Case("r0", AVR::R1R0).Case("r2", AVR::R3R2)
+      .Case("r4", AVR::R5R4).Case("r6", AVR::R7R6)
+      .Case("r8", AVR::R9R8).Case("r10", AVR::R11R10)
+      .Case("r12", AVR::R13R12).Case("r14", AVR::R15R14)
+      .Case("r16", AVR::R17R16).Case("r18", AVR::R19R18)
+      .Case("r20", AVR::R21R20).Case("r22", AVR::R23R22)
+      .Case("r24", AVR::R25R24).Case("r26", AVR::R27R26)
+      .Case("r28", AVR::R29R28).Case("r30", AVR::R31R30)
+      .Case("X", AVR::R27R26).Case("Y", AVR::R29R28).Case("Z", AVR::R31R30)
+      .Default(0);
+  }
+
+  if (Reg)
+    return Reg;
+
+  report_fatal_error("Invalid register name global variable");
+}
+
 } // end of namespace llvm
 
diff --git a/llvm/lib/Target/AVR/AVRISelLowering.h b/llvm/lib/Target/AVR/AVRISelLowering.h
index 17074e1b1ee..a8cdc4e7ae2 100644
--- a/llvm/lib/Target/AVR/AVRISelLowering.h
+++ b/llvm/lib/Target/AVR/AVRISelLowering.h
@@ -116,6 +116,9 @@ public:
                                     std::vector<SDValue> &Ops,
                                     SelectionDAG &DAG) const override;
 
+  unsigned getRegisterByName(const char* RegName, EVT VT,
+                             SelectionDAG &DAG) const override;
+
 private:
   SDValue getAVRCmp(SDValue LHS, SDValue RHS, ISD::CondCode CC, SDValue &AVRcc,
                     SelectionDAG &DAG, SDLoc dl) const;
diff --git a/llvm/test/CodeGen/AVR/intrinsics/read_register.ll b/llvm/test/CodeGen/AVR/intrinsics/read_register.ll
new file mode 100644
index 00000000000..3f28d1d3a9f
--- /dev/null
+++ b/llvm/test/CodeGen/AVR/intrinsics/read_register.ll
@@ -0,0 +1,17 @@
+; RUN: llc -O0 < %s -march=avr | FileCheck %s
+
+; CHECK-LABEL: foo
+define void @foo() {
+entry:
+  %val1 = call i16 @llvm.read_register.i16(metadata !0)
+  %val2 = call i16 @llvm.read_register.i16(metadata !1)
+  %val3 = call i8 @llvm.read_register.i8(metadata !2)
+  ret void
+}
+
+declare i8 @llvm.read_register.i8(metadata)
+declare i16 @llvm.read_register.i16(metadata)
+
+!0 = !{!"r28"}
+!1 = !{!"Z"}
+!2 = !{!"r0"}