[mips] Add preliminary support for the MIPS II target.

Summary:
This patch enables code generation for the MIPS II target. Pre-Mips32
targets don't have the MUL instruction, so we add the correspondent
pattern that uses the MULT/MFLO combination in order to retrieve the
product.

This is WIP as we don't support code generation for select nodes due to
the lack of conditional-move instructions.

Reviewers: dsanders

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D6150

llvm-svn: 221686

3 files changed, 13 insertions, 5 deletions

diff --git a/llvm/lib/Target/Mips/MipsInstrInfo.td b/llvm/lib/Target/Mips/MipsInstrInfo.td
index c89da01a61c..93ea6f6e8e6 100644
--- a/llvm/lib/Target/Mips/MipsInstrInfo.td
+++ b/llvm/lib/Target/Mips/MipsInstrInfo.td
@@ -1653,6 +1653,12 @@ let AdditionalPredicates = [NotDSP] in {
                 (ADDiu GPR32:$src, imm:$imm)>;
 }
 
+// Support multiplication for pre-Mips32 targets that don't have
+// the MUL instruction.
+def : MipsPat<(mul GPR32:$lhs, GPR32:$rhs),
+              (PseudoMFLO (PseudoMULT GPR32:$lhs, GPR32:$rhs))>,
+      ISA_MIPS1_NOT_32R6_64R6;
+
 // SYNC
 def : MipsPat<(MipsSync (i32 immz)),
               (SYNC 0)>, ISA_MIPS2;
diff --git a/llvm/lib/Target/Mips/MipsSubtarget.cpp b/llvm/lib/Target/Mips/MipsSubtarget.cpp
index ab8c03a1c50..8768b12f7d1 100644
--- a/llvm/lib/Target/Mips/MipsSubtarget.cpp
+++ b/llvm/lib/Target/Mips/MipsSubtarget.cpp
@@ -109,7 +109,7 @@ static std::string computeDataLayout(const MipsSubtarget &ST) {
 MipsSubtarget::MipsSubtarget(const std::string &TT, const std::string &CPU,
                              const std::string &FS, bool little,
                              const MipsTargetMachine *_TM)
-    : MipsGenSubtargetInfo(TT, CPU, FS), MipsArchVersion(Mips32),
+    : MipsGenSubtargetInfo(TT, CPU, FS), MipsArchVersion(MipsDefault),
       ABI(MipsABIInfo::Unknown()), IsLittle(little), IsSingleFloat(false),
       IsFPXX(false), NoABICalls(false), IsFP64bit(false), UseOddSPReg(true),
       IsNaN2008bit(false), IsGP64bit(false), HasVFPU(false), HasCnMips(false),
@@ -126,13 +126,14 @@ MipsSubtarget::MipsSubtarget(const std::string &TT, const std::string &CPU,
 
   PreviousInMips16Mode = InMips16Mode;
 
-  // Don't even attempt to generate code for MIPS-I, MIPS-II, MIPS-III, and
-  // MIPS-V. They have not been tested and currently exist for the integrated
+  if (MipsArchVersion == MipsDefault)
+    MipsArchVersion = Mips32;
+
+  // Don't even attempt to generate code for MIPS-I, MIPS-III and MIPS-V.
+  // They have not been tested and currently exist for the integrated
   // assembler only.
   if (MipsArchVersion == Mips1)
     report_fatal_error("Code generation for MIPS-I is not implemented", false);
-  if (MipsArchVersion == Mips2)
-    report_fatal_error("Code generation for MIPS-II is not implemented", false);
   if (MipsArchVersion == Mips3)
     report_fatal_error("Code generation for MIPS-III is not implemented",
                        false);
diff --git a/llvm/lib/Target/Mips/MipsSubtarget.h b/llvm/lib/Target/Mips/MipsSubtarget.h
index 1c37b84940e..bff90135f9c 100644
--- a/llvm/lib/Target/Mips/MipsSubtarget.h
+++ b/llvm/lib/Target/Mips/MipsSubtarget.h
@@ -37,6 +37,7 @@ class MipsSubtarget : public MipsGenSubtargetInfo {
   virtual void anchor();
 
   enum MipsArchEnum {
+    MipsDefault,
     Mips1, Mips2, Mips32, Mips32r2, Mips32r6, Mips3, Mips4, Mips5, Mips64,
     Mips64r2, Mips64r6
   };