ARM: add @llvm.arm.space intrinsic for testing ConstantIslands.

Creating tests for the ConstantIslands pass is very difficult, since it depends
on precise layout details. Having the ability to precisely inject a number of
bytes into the stream helps greatly.

llvm-svn: 221903

llvm/include/llvm/IR/IntrinsicsARM.td

@@ -20,6 +20,11 @@ let TargetPrefix = "arm" in {  // All intrinsics start with "llvm.arm.".
 def int_arm_thread_pointer : GCCBuiltin<"__builtin_thread_pointer">,
             Intrinsic<[llvm_ptr_ty], [], [IntrNoMem]>;
 
+// A space-consuming intrinsic primarily for testing ARMConstantIslands. The
+// first argument is the number of bytes this "instruction" takes up, the second
+// and return value are essentially chains, used to force ordering during ISel.
+def int_arm_space : Intrinsic<[llvm_i32_ty], [llvm_i32_ty, llvm_i32_ty], []>;
+
 //===----------------------------------------------------------------------===//
 // Saturating Arithmetic
 

llvm/lib/Target/ARM/ARMAsmPrinter.cpp

@@ -1592,6 +1592,9 @@ void ARMAsmPrinter::EmitInstruction(const MachineInstr *MI) {
     EmitJumpTable(MI);
     return;
   }
+  case ARM::SPACE:
+    OutStreamer.EmitZeros(MI->getOperand(1).getImm());
+    return;
   case ARM::TRAP: {
     // Non-Darwin binutils don't yet support the "trap" mnemonic.
     // FIXME: Remove this special case when they do.

llvm/lib/Target/ARM/ARMBaseInstrInfo.cpp

@@ -674,6 +674,8 @@ unsigned ARMBaseInstrInfo::GetInstSizeInBytes(const MachineInstr *MI) const {
       ++NumEntries;
     return NumEntries * EntrySize + InstSize;
   }
+  case ARM::SPACE:
+    return MI->getOperand(1).getImm();
   }
 }
 

llvm/lib/Target/ARM/ARMInstrInfo.td

@@ -5621,3 +5621,8 @@ def : InstAlias<"umull${s}${p} $RdLo, $RdHi, $Rn, $Rm",
 // is discarded.
 def ITasm : ARMAsmPseudo<"it$mask $cc", (ins it_pred:$cc, it_mask:$mask)>,
          ComplexDeprecationPredicate<"IT">;
+
+let mayLoad = 1, mayStore =1, hasSideEffects = 1 in
+def SPACE : PseudoInst<(outs GPR:$Rd), (ins i32imm:$size, GPR:$Rn),
+                       NoItinerary,
+                       [(set GPR:$Rd, (int_arm_space imm:$size, GPR:$Rn))]>;

llvm/test/CodeGen/ARM/space-directive.ll

@@ -0,0 +1,19 @@
+; RUN: llc -mtriple=armv7 -o - %s | FileCheck %s
+
+define i32 @test_space() minsize {
+; CHECK-LABEL: test_space:
+; CHECK: ldr {{r[0-9]+}}, [[CPENTRY:.?LCPI[0-9]+_[0-9]+]]
+; CHECK: b [[PAST_CP:.?LBB[0-9]+_[0-9]+]]
+
+; CHECK: [[CPENTRY]]:
+; CHECK-NEXT: 12345678
+
+; CHECK: [[PAST_CP]]:
+; CHECK: .zero 10000
+  %addr = inttoptr i32 12345678 to i32*
+  %val = load i32* %addr
+  call i32 @llvm.arm.space(i32 10000, i32 undef)
+  ret i32 %val
+}
+
+declare i32 @llvm.arm.space(i32, i32)