[RISCV] Implement adding a displacement to a BlockAddress

[rogfer01]

Summary

Recent change rL357393 uses MachineInstrBuilder::addDisp to add a based on a BlockAddress but this case was not implemented.

This patch adds the missing case and a test for RISC-V that exercises the new case.

[lewis-revill]

Thanks, I didn't realise this was the case.

test/CodeGen/RISCV/codemodel-lowering.ll

126

Is this phi node necessary for the test?

[rogfer01]

ChangeLog

• Remove dead phi in the test

[asb]

Thanks Roger, this looks good to me.

[rogfer01]

Lewis, Alex: thanks for the review.

I will commit it shortly.

include/llvm/CodeGen/MachineInstrBuilder.h

switch (Disp.getType()) {
       case MachineOperand::MO_Immediate:
         return addImm(Disp.getImm() + off);
       case MachineOperand::MO_ConstantPoolIndex:
         return addConstantPoolIndex(Disp.getIndex(), Disp.getOffset() + off,
                                     TargetFlags);
       case MachineOperand::MO_GlobalAddress:
         return addGlobalAddress(Disp.getGlobal(), Disp.getOffset() + off,
                                 TargetFlags);
+      case MachineOperand::MO_BlockAddress:
+        return addBlockAddress(Disp.getBlockAddress(), Disp.getOffset() + off,
+                               TargetFlags);
     }
   }
 
   /// Copy all the implicit operands from OtherMI onto this one.
   const MachineInstrBuilder &
   copyImplicitOps(const MachineInstr &OtherMI) const {
     MI->copyImplicitOps(*MF, OtherMI);
     return *this;

test/CodeGen/RISCV/codemodel-lowering.ll

 ; RV32I-MEDIUM-NEXT:    ret
   store volatile i8* blockaddress(@lower_blockaddress, %block), i8** @addr
   ret void
 
 block:
   unreachable
 }
 
+; Check lowering of blockaddress that forces a displacement to be added
+
+define signext i32 @lower_blockaddress_displ(i32 signext %w) nounwind {
+; RV32I-SMALL-LABEL: lower_blockaddress_displ:
+; RV32I-SMALL:       # %bb.0: # %entry
+; RV32I-SMALL-NEXT:    addi sp, sp, -16
+; RV32I-SMALL-NEXT:    sw ra, 12(sp)
+; RV32I-SMALL-NEXT:    lui a1, %hi(.Ltmp0)
+; RV32I-SMALL-NEXT:    addi a1, a1, %lo(.Ltmp0)
+; RV32I-SMALL-NEXT:    sw a1, 8(sp)
+; RV32I-SMALL-NEXT:    addi a1, zero, 101
+; RV32I-SMALL-NEXT:    blt a0, a1, .LBB2_3
+; RV32I-SMALL-NEXT:  # %bb.1: # %if.then
+; RV32I-SMALL-NEXT:    lw a0, 8(sp)
+; RV32I-SMALL-NEXT:    jr a0
+; RV32I-SMALL-NEXT:  .Ltmp0: # Block address taken
+; RV32I-SMALL-NEXT:  .LBB2_2: # %return
+; RV32I-SMALL-NEXT:    addi a0, zero, 4
+; RV32I-SMALL-NEXT:    j .LBB2_4
+; RV32I-SMALL-NEXT:  .LBB2_3: # %return.clone
+; RV32I-SMALL-NEXT:    addi a0, zero, 3
+; RV32I-SMALL-NEXT:  .LBB2_4: # %.split
+; RV32I-SMALL-NEXT:    lw ra, 12(sp)
+; RV32I-SMALL-NEXT:    addi sp, sp, 16
+; RV32I-SMALL-NEXT:    ret
+;
+; RV32I-MEDIUM-LABEL: lower_blockaddress_displ:
+; RV32I-MEDIUM:       # %bb.0: # %entry
+; RV32I-MEDIUM-NEXT:    addi sp, sp, -16
+; RV32I-MEDIUM-NEXT:    sw ra, 12(sp)
+; RV32I-MEDIUM-NEXT:  .LBB2_5: # %entry
+; RV32I-MEDIUM-NEXT:    # Label of block must be emitted
+; RV32I-MEDIUM-NEXT:    auipc a1, %pcrel_hi(.Ltmp0)
+; RV32I-MEDIUM-NEXT:    addi a1, a1, %pcrel_lo(.LBB2_5)
+; RV32I-MEDIUM-NEXT:    sw a1, 8(sp)
+; RV32I-MEDIUM-NEXT:    addi a1, zero, 101
+; RV32I-MEDIUM-NEXT:    blt a0, a1, .LBB2_3
+; RV32I-MEDIUM-NEXT:  # %bb.1: # %if.then
+; RV32I-MEDIUM-NEXT:    lw a0, 8(sp)
+; RV32I-MEDIUM-NEXT:    jr a0
+; RV32I-MEDIUM-NEXT:  .Ltmp0: # Block address taken
+; RV32I-MEDIUM-NEXT:  .LBB2_2: # %return
+; RV32I-MEDIUM-NEXT:    addi a0, zero, 4
+; RV32I-MEDIUM-NEXT:    j .LBB2_4
+; RV32I-MEDIUM-NEXT:  .LBB2_3: # %return.clone
+; RV32I-MEDIUM-NEXT:    addi a0, zero, 3
+; RV32I-MEDIUM-NEXT:  .LBB2_4: # %.split
+; RV32I-MEDIUM-NEXT:    lw ra, 12(sp)
+; RV32I-MEDIUM-NEXT:    addi sp, sp, 16
+; RV32I-MEDIUM-NEXT:    ret
+entry:
+  %x = alloca i8*, align 8
+  store i8* blockaddress(@lower_blockaddress_displ, %test_block), i8** %x, align 8
+  %cmp = icmp sgt i32 %w, 100
+  br i1 %cmp, label %if.then, label %if.end
+
+if.then:
+  %addr = load i8*, i8** %x, align 8
+  br label %indirectgoto
+
+if.end:
+  br label %return
+
+test_block:
+  br label %return
+
+return:
+  %retval = phi i32 [ 3, %if.end ], [ 4, %test_block ]
+  ret i32 %retval
+
+indirectgoto:
+  %indirect.goto.dest = phi i8* [ %addr, %if.then ]
+  indirectbr i8* %addr, [ label %test_block ]
+}
+
 ; Check lowering of constantpools
 
 define float @lower_constantpool(float %a) nounwind {
 ; RV32I-SMALL-LABEL: lower_constantpool:
 ; RV32I-SMALL:       # %bb.0:
 ; RV32I-SMALL-NEXT:    fmv.w.x ft0, a0
-; RV32I-SMALL-NEXT:    lui a0, %hi(.LCPI2_0)
-; RV32I-SMALL-NEXT:    addi a0, a0, %lo(.LCPI2_0)
+; RV32I-SMALL-NEXT:    lui a0, %hi(.LCPI3_0)
+; RV32I-SMALL-NEXT:    addi a0, a0, %lo(.LCPI3_0)
 ; RV32I-SMALL-NEXT:    flw ft1, 0(a0)
 ; RV32I-SMALL-NEXT:    fadd.s ft0, ft0, ft1
 ; RV32I-SMALL-NEXT:    fmv.x.w a0, ft0
 ; RV32I-SMALL-NEXT:    ret
 ;
 ; RV32I-MEDIUM-LABEL: lower_constantpool:
 ; RV32I-MEDIUM:       # %bb.0:
-; RV32I-MEDIUM-NEXT:  .LBB2_1: # Label of block must be emitted
-; RV32I-MEDIUM-NEXT:    auipc a1, %pcrel_hi(.LCPI2_0)
-; RV32I-MEDIUM-NEXT:    addi a1, a1, %pcrel_lo(.LBB2_1)
+; RV32I-MEDIUM-NEXT:  .LBB3_1: # Label of block must be emitted
+; RV32I-MEDIUM-NEXT:    auipc a1, %pcrel_hi(.LCPI3_0)
+; RV32I-MEDIUM-NEXT:    addi a1, a1, %pcrel_lo(.LBB3_1)
 ; RV32I-MEDIUM-NEXT:    flw ft0, 0(a1)
 ; RV32I-MEDIUM-NEXT:    fmv.w.x ft1, a0
 ; RV32I-MEDIUM-NEXT:    fadd.s ft0, ft1, ft0
 ; RV32I-MEDIUM-NEXT:    fmv.x.w a0, ft0
 ; RV32I-MEDIUM-NEXT:    ret
   %1 = fadd float %a, 1.0
   ret float %1
 }