[PowerPC] mark r+i as legal address mode for vector type after pwr9

[shchenz]

Summary

After p9, we have DQ form lxv and stxv which is a legal r+i address mode for vector type.

Add this address mode to PPCTargetLowering::isLegalAddressingMode

This will impact LSR about DQ form instructions generation.

[shchenz]

delete no necessary hasP10Vector()

[steven.zhang]

LGTM. Thank you for addressing this.

llvm/lib/Target/PowerPC/PPCISelLowering.cpp

void PPCTargetLowering::LowerAsmOperandForConstraint(SDValue Op,
   // Handle standard constraint letters.
   TargetLowering::LowerAsmOperandForConstraint(Op, Constraint, Ops, DAG);
 }
 
 // isLegalAddressingMode - Return true if the addressing mode represented
 // by AM is legal for this target, for a load/store of the specified type.
 bool PPCTargetLowering::isLegalAddressingMode(const DataLayout &DL,
                                               const AddrMode &AM, Type *Ty,
-                                              unsigned AS, Instruction *I) const {
-  // PPC does not allow r+i addressing modes for vectors!
-  if (Ty->isVectorTy() && AM.BaseOffs != 0)
+                                              unsigned AS,
+                                              Instruction *I) const {
+  // Vector type r+i form is supported since power9 as DQ form. We don't check
+  // the offset matching DQ form requirement(off % 16 == 0), because on PowerPC,
+  // imm form is preferred and the offset can be adjusted to use imm form later
+  // in pass PPCLoopInstrFormPrep. Also in LSR, for one LSRUse, it uses min and
+  // max offset to check legal addressing mode, we should be a little aggressive
+  // to contain other offsets for that LSRUse.
+  if (Ty->isVectorTy() && AM.BaseOffs != 0 &&
+      !(Subtarget.hasP9Vector() || Subtarget.hasP10Vector()))
     return false;
 
   // PPC allows a sign-extended 16-bit immediate field.
   if (AM.BaseOffs <= -(1LL << 16) || AM.BaseOffs >= (1LL << 16)-1)
     return false;
 
   // No global is ever allowed as a base.
   if (AM.BaseGV)

llvm/test/CodeGen/PowerPC/prefer-dqform.ll

 ; RUN: llc -verify-machineinstrs -disable-ppc-instr-form-prep=true -mcpu=pwr9 < %s \
 ; RUN:   -ppc-vsr-nums-as-vr -ppc-asm-full-reg-names | FileCheck %s -check-prefix=CHECK-P9
 ; RUN: llc -verify-machineinstrs -disable-ppc-instr-form-prep=true -mcpu=pwr10 < %s \
 ; RUN:   -ppc-vsr-nums-as-vr -ppc-asm-full-reg-names | FileCheck %s -check-prefix=CHECK-P10
 
 target triple = "powerpc64le-unknown-linux-gnu"
 
 %_elem_type_of_a = type <{ double }>
 %_elem_type_of_x = type <{ double }>
 %_elem_type_of_y = type <{ double }>
 
 define void @test(i32* dereferenceable(4) %.ial, i32* noalias dereferenceable(4) %.m, i32* noalias dereferenceable(4) %.n, [0 x %_elem_type_of_a]*  %.a, i32* noalias dereferenceable(4) %.lda, [0 x %_elem_type_of_x]* noalias %.x, [0 x %_elem_type_of_y]* noalias %.y) {
 ; CHECK-P9-LABEL: test:
 ; CHECK-P9:       .LBB0_2: # %_loop_2_do_
-; CHECK-P9:         lxvx
-; CHECK-P9:         lxvx
-; CHECK-P9-DAG:     lxvx
-; CHECK-P9-DAG:     lxvx
-; CHECK-P9-DAG:     xvmaddadp
-; CHECK-P9-DAG:     xvmaddadp
-; CHECK-P9-DAG:     stxvx
-; CHECK-P9:         stxvx
+; CHECK-P9:         lxv vs1, -16(r4)
+; CHECK-P9:         lxv vs2, 0(r4)
+; CHECK-P9-DAG:     lxv vs3, -16(r3)
+; CHECK-P9-DAG:     lxv vs4, 0(r3)
+; CHECK-P9-DAG:     xvmaddadp vs1, vs3, vs1
+; CHECK-P9-DAG:     stxv vs1, -16(r4)
+; CHECK-P9-DAG:     xvmaddadp vs2, vs4, vs0
+; CHECK-P9:         stxv vs2, 0(r4)
 ; CHECK-P9:         bdnz .LBB0_2
 ;
+; FIXME: use pair load/store instructions lxvp/stxvp
 ; CHECK-P10-LABEL: test:
 ; CHECK-P10:       .LBB0_2: # %_loop_2_do_
-; CHECK-P10:         lxvx
-; CHECK-P10:         lxvx
-; CHECK-P10-DAG:     lxvx
-; CHECK-P10-DAG:     lxvx
-; CHECK-P10-DAG:     xvmaddadp
-; CHECK-P10-DAG:     xvmaddadp
-; CHECK-P10-DAG:     stxvx
-; CHECK-P10:         stxvx
+; CHECK-P10:         lxv vs1, -16(r4)
+; CHECK-P10:         lxv vs2, 0(r4)
+; CHECK-P10-DAG:     lxv vs3, -16(r3)
+; CHECK-P10-DAG:     lxv vs4, 0(r3)
+; CHECK-P10-DAG:     xvmaddadp vs1, vs3, vs1
+; CHECK-P10-DAG:     xvmaddadp vs2, vs4, vs0
+; CHECK-P10-DAG:     stxv vs1, -16(r4)
+; CHECK-P10:         stxv vs2, 0(r4)
 ; CHECK-P10:         bdnz .LBB0_2
 test_entry:
   %_conv5 = ptrtoint [0 x %_elem_type_of_a]* %.a to i64
   %_andi_tmp = and i64 %_conv5, 15
   %_equ_tmp = icmp eq i64 %_andi_tmp, 0
   %. = select i1 %_equ_tmp, i32 1, i32 2
   %_val_m_ = load i32, i32* %.m, align 4
   %_sub_tmp9 = sub nsw i32 1, %.