[mips] Sign extend i32 return values on MIPS64

Override getTypeForExtReturn so that functions returning
an i32 typed value have it sign extended on MIPS64.

Also provide patterns to get rid of unneeded sign extensions
for arithmetic instructions which implicitly sign extend
their results.

Differential Revision: https://reviews.llvm.org/D48374

llvm-svn: 338019

4 files changed, 64 insertions, 0 deletions

diff --git a/llvm/lib/Target/Mips/Mips64InstrInfo.td b/llvm/lib/Target/Mips/Mips64InstrInfo.td
index bc80098ade8..878ec29b188 100644
--- a/llvm/lib/Target/Mips/Mips64InstrInfo.td
+++ b/llvm/lib/Target/Mips/Mips64InstrInfo.td
@@ -825,6 +825,45 @@ def : MipsPat<(atomic_store_32 addr:$a, GPR64:$v), (SW64 GPR64:$v, addr:$a)>,
 def : MipsPat<(atomic_store_64 addr:$a, GPR64:$v), (SD GPR64:$v, addr:$a)>,
       ISA_MIPS3, GPR_64;
 
+// Patterns used for matching away redundant sign extensions.
+// MIPS32 arithmetic instructions sign extend their result implicitly.
+def : MipsPat<(i64 (sext (i32 (add GPR32:$src, immSExt16:$imm16)))),
+              (INSERT_SUBREG (i64 (IMPLICIT_DEF)),
+              (ADDiu GPR32:$src, immSExt16:$imm16), sub_32)>;
+def : MipsPat<(i64 (sext (i32 (add GPR32:$src, GPR32:$src2)))),
+              (INSERT_SUBREG (i64 (IMPLICIT_DEF)),
+              (ADDu GPR32:$src, GPR32:$src2), sub_32)>;
+def : MipsPat<(i64 (sext (i32 (sub GPR32:$src, GPR32:$src2)))),
+              (INSERT_SUBREG (i64 (IMPLICIT_DEF)),
+              (SUBu GPR32:$src, GPR32:$src2), sub_32)>;
+def : MipsPat<(i64 (sext (i32 (mul GPR32:$src, GPR32:$src2)))),
+              (INSERT_SUBREG (i64 (IMPLICIT_DEF)),
+              (MUL GPR32:$src, GPR32:$src2), sub_32)>;
+def : MipsPat<(i64 (sext (i32 (MipsMFHI ACC64:$src)))),
+              (INSERT_SUBREG (i64 (IMPLICIT_DEF)),
+              (PseudoMFHI ACC64:$src), sub_32)>;
+def : MipsPat<(i64 (sext (i32 (MipsMFLO ACC64:$src)))),
+              (INSERT_SUBREG (i64 (IMPLICIT_DEF)),
+              (PseudoMFLO ACC64:$src), sub_32)>;
+def : MipsPat<(i64 (sext (i32 (shl GPR32:$src, immZExt5:$imm5)))),
+              (INSERT_SUBREG (i64 (IMPLICIT_DEF)),
+              (SLL GPR32:$src, immZExt5:$imm5), sub_32)>;
+def : MipsPat<(i64 (sext (i32 (shl GPR32:$src, GPR32:$src2)))),
+              (INSERT_SUBREG (i64 (IMPLICIT_DEF)),
+              (SLLV GPR32:$src, GPR32:$src2), sub_32)>;
+def : MipsPat<(i64 (sext (i32 (srl GPR32:$src, immZExt5:$imm5)))),
+              (INSERT_SUBREG (i64 (IMPLICIT_DEF)),
+              (SRL GPR32:$src, immZExt5:$imm5), sub_32)>;
+def : MipsPat<(i64 (sext (i32 (srl GPR32:$src, GPR32:$src2)))),
+              (INSERT_SUBREG (i64 (IMPLICIT_DEF)),
+              (SRLV GPR32:$src, GPR32:$src2), sub_32)>;
+def : MipsPat<(i64 (sext (i32 (sra GPR32:$src, immZExt5:$imm5)))),
+              (INSERT_SUBREG (i64 (IMPLICIT_DEF)),
+              (SRA GPR32:$src, immZExt5:$imm5), sub_32)>;
+def : MipsPat<(i64 (sext (i32 (sra GPR32:$src, GPR32:$src2)))),
+              (INSERT_SUBREG (i64 (IMPLICIT_DEF)),
+              (SRAV GPR32:$src, GPR32:$src2), sub_32)>;
+
 //===----------------------------------------------------------------------===//
 // Instruction aliases
 //===----------------------------------------------------------------------===//
diff --git a/llvm/lib/Target/Mips/Mips64r6InstrInfo.td b/llvm/lib/Target/Mips/Mips64r6InstrInfo.td
index 853702c30dd..9df802cc30b 100644
--- a/llvm/lib/Target/Mips/Mips64r6InstrInfo.td
+++ b/llvm/lib/Target/Mips/Mips64r6InstrInfo.td
@@ -299,6 +299,21 @@ def : MipsPat<(select (i32 (seteq i32:$cond, immz)), immz, i64:$f),
               (SELNEZ64 i64:$f, (SLL64_32 i32:$cond))>,
               ISA_MIPS64R6;
 
+// Patterns used for matching away redundant sign extensions.
+// MIPS32 arithmetic instructions sign extend their result implicitly.
+def : MipsPat<(i64 (sext (i32 (sdiv GPR32:$src, GPR32:$src2)))),
+              (INSERT_SUBREG (i64 (IMPLICIT_DEF)),
+              (DIV GPR32:$src, GPR32:$src2), sub_32)>, ISA_MIPS64R6;
+def : MipsPat<(i64 (sext (i32 (udiv GPR32:$src, GPR32:$src2)))),
+              (INSERT_SUBREG (i64 (IMPLICIT_DEF)),
+              (DIVU GPR32:$src, GPR32:$src2), sub_32)>, ISA_MIPS64R6;
+def : MipsPat<(i64 (sext (i32 (srem GPR32:$src, GPR32:$src2)))),
+              (INSERT_SUBREG (i64 (IMPLICIT_DEF)),
+              (MOD GPR32:$src, GPR32:$src2), sub_32)>, ISA_MIPS64R6;
+def : MipsPat<(i64 (sext (i32 (urem GPR32:$src, GPR32:$src2)))),
+              (INSERT_SUBREG (i64 (IMPLICIT_DEF)),
+              (MODU GPR32:$src, GPR32:$src2), sub_32)>, ISA_MIPS64R6;
+
 // Pseudo instructions
 
 let AdditionalPredicates = [NotInMips16Mode, NotInMicroMips,
diff --git a/llvm/lib/Target/Mips/MipsISelLowering.cpp b/llvm/lib/Target/Mips/MipsISelLowering.cpp
index ba4dbefa21a..9ffc38356b7 100644
--- a/llvm/lib/Target/Mips/MipsISelLowering.cpp
+++ b/llvm/lib/Target/Mips/MipsISelLowering.cpp
@@ -3714,6 +3714,13 @@ static std::pair<bool, bool> parsePhysicalReg(StringRef C, StringRef &Prefix,
                         true);
 }
 
+EVT MipsTargetLowering::getTypeForExtReturn(LLVMContext &Context, EVT VT,
+                                            ISD::NodeType) const {
+  bool Cond = !Subtarget.isABI_O32() && VT.getSizeInBits() == 32;
+  EVT MinVT = getRegisterType(Context, Cond ? MVT::i64 : MVT::i32);
+  return VT.bitsLT(MinVT) ? MinVT : VT;
+}
+
 std::pair<unsigned, const TargetRegisterClass *> MipsTargetLowering::
 parseRegForInlineAsmConstraint(StringRef C, MVT VT) const {
   const TargetRegisterInfo *TRI =
diff --git a/llvm/lib/Target/Mips/MipsISelLowering.h b/llvm/lib/Target/Mips/MipsISelLowering.h
index 7e5d6a2a017..b58d92c370d 100644
--- a/llvm/lib/Target/Mips/MipsISelLowering.h
+++ b/llvm/lib/Target/Mips/MipsISelLowering.h
@@ -280,6 +280,9 @@ class TargetRegisterClass;
       return MVT::i32;
     }
 
+    EVT getTypeForExtReturn(LLVMContext &Context, EVT VT,
+                            ISD::NodeType) const override;
+
     bool isCheapToSpeculateCttz() const override;
     bool isCheapToSpeculateCtlz() const override;