[ARM] Mark LEApcrel as not having side effects

[john.brawn]

Summary

Doing this lets us hoist it out of loops, and I've also marked it as rematerializable the same as the thumb1 and thumb2 counterparts.

It looks like it being marked as such was just a mistake, as the commit that made that change only mentions LEApcrelJT and in thumb2 only the t2LEApcrelJT instruction was marked as having side-effects, so it looks like the intent was to only mark LEApcrelJT as having side-effects but LEApcrel was accidentally marked as such also.

[john.brawn]

Ping.

[jmolloy]

LGTM

lib/Target/ARM/ARMInstrInfo.td

def ADR : AI1<{0,?,?,0}, (outs GPR:$Rd), (ins adrlabel:$label),
   let Inst{23-22} = label{13-12};
   let Inst{21} = 0;
   let Inst{20} = 0;
   let Inst{19-16} = 0b1111;
   let Inst{15-12} = Rd;
   let Inst{11-0} = label{11-0};
 }
 
-let hasSideEffects = 1 in {
+let hasSideEffects = 0, isReMaterializable = 1 in
 def LEApcrel : ARMPseudoInst<(outs GPR:$Rd), (ins i32imm:$label, pred:$p),
                     4, IIC_iALUi, []>, Sched<[WriteALU, ReadALU]>;
 
+let hasSideEffects = 1 in
 def LEApcrelJT : ARMPseudoInst<(outs GPR:$Rd),
                       (ins i32imm:$label, pred:$p),
                       4, IIC_iALUi, []>, Sched<[WriteALU, ReadALU]>;
-}
 
 //===----------------------------------------------------------------------===//
 //  Control Flow Instructions.
 //
 
 let isReturn = 1, isTerminator = 1, isBarrier = 1 in {
   // ARMV4T and above
   def BX_RET : AI<(outs), (ins), BrMiscFrm, IIC_Br,

test/CodeGen/ARM/adr-hoist.ll

+; RUN: llc -mtriple=armv7a   %s -o - | FileCheck %s
+; RUN: llc -mtriple=thumbv7m %s -o - | FileCheck %s
+; RUN: llc -mtriple=thumbv6m %s -o - | FileCheck %s
+
+@arr = internal unnamed_addr constant [4 x i32] [i32 305419896, i32 -1430532899, i32 -2023406815, i32 -573785174], align 4
+
+; Check that the adr of arr is hoisted out of the loop
+; CHECK: adr [[REG:r[0-9]+]], .LCP
+; CHECK: .LBB
+; CHECK-NOT adr
+; CHECK: ldr{{(.w)?}} {{r[0-9]+}}, {{\[}}[[REG]],
+
+define void @fn(i32 %n, i32* %p) {
+entry:
+  %cmp8 = icmp sgt i32 %n, 0
+  br i1 %cmp8, label %for.body, label %for.cond.cleanup
+
+for.body:
+  %i.09 = phi i32 [ %inc, %for.body ], [ 0, %entry ]
+  %arrayidx = getelementptr inbounds i32, i32* %p, i32 %i.09
+  %0 = load i32, i32* %arrayidx, align 4
+  %arrayidx1 = getelementptr inbounds [4 x i32], [4 x i32]* @arr, i32 0, i32 %0
+  %1 = load i32, i32* %arrayidx1, align 4
+  store i32 %1, i32* %arrayidx, align 4
+  %inc = add nuw nsw i32 %i.09, 1
+  %exitcond = icmp eq i32 %inc, %n
+  br i1 %exitcond, label %for.cond.cleanup, label %for.body
+
+for.cond.cleanup:
+  ret void
+}