[RISCV] Exclude LPAD in machine outliner (#157220)

After #139993, the
RISCVIndirectBranchTracking pass is also ran before the Machine Outliner
pass, this yield a possibility that the outliner could also outline the
LPAD instruction that should be placed at the target of an indirect
branch. This patch excludes LPAD instruction from the candidate of
machine outliner.

Author: jaidTw

llvm/lib/Target/RISCV/RISCVInstrInfo.cpp

@@ -3511,6 +3511,9 @@ RISCVInstrInfo::getOutliningTypeImpl(const MachineModuleInfo &MMI,
       return outliner::InstrType::Illegal;
   }
 
+  if (isLPAD(MI))
+    return outliner::InstrType::Illegal;
+
   return outliner::InstrType::Legal;
 }
 

llvm/lib/Target/RISCV/RISCVInstrPredicates.td

@@ -148,6 +148,14 @@ def isNonZeroLoadImmediate
                      CheckNot<CheckImmOperand<2, 0>>
                    ]>>>;
 
+def isLPAD
+    : TIIPredicate<"isLPAD",
+                   MCReturnStatement<CheckAll<[
+                     CheckOpcode<[AUIPC]>,
+                     CheckIsRegOperand<0>,
+                     CheckRegOperand<0, X0>,
+                   ]>>>;
+
 def ignoresVXRM
     : TIIPredicate<"ignoresVXRM",
                    MCOpcodeSwitchStatement<

llvm/test/CodeGen/RISCV/machine-outliner-lpad.ll

@@ -0,0 +1,65 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --version 5
+; RUN: llc -mtriple riscv64 -mattr=+experimental-zicfilp < %s | FileCheck %s
+; RUN: llc -mtriple riscv32 -mattr=+experimental-zicfilp < %s | FileCheck %s
+
+define i16 @test1(i16 %x) #0 {
+; CHECK-LABEL: test1:
+; CHECK:       # %bb.0: # %entry
+; CHECK-NEXT:    lpad 0
+; CHECK-NEXT:    tail OUTLINED_FUNCTION_0
+entry:
+  %y = add i16 5, %x
+  %z = mul i16 4, %y
+  ret i16 %z
+}
+
+define i16 @test2(i16 %x) #0 {
+; CHECK-LABEL: test2:
+; CHECK:       # %bb.0: # %entry
+; CHECK-NEXT:    lpad 0
+; CHECK-NEXT:    tail OUTLINED_FUNCTION_0
+entry:
+  %y = add i16 5, %x
+  %z = mul i16 4, %y
+  ret i16 %z
+}
+
+define i16 @test3(i16 %x) #0 {
+; CHECK-LABEL: test3:
+; CHECK:       # %bb.0: # %entry
+; CHECK-NEXT:    lpad 0
+; CHECK-NEXT:    tail OUTLINED_FUNCTION_0
+entry:
+  %y = add i16 5, %x
+  %z = mul i16 4, %y
+  ret i16 %z
+}
+
+define i16 @test4(i16 %x) #0 {
+; CHECK-LABEL: test4:
+; CHECK:       # %bb.0: # %entry
+; CHECK-NEXT:    lpad 0
+; CHECK-NEXT:    tail OUTLINED_FUNCTION_0
+entry:
+  %y = add i16 5, %x
+  %z = mul i16 4, %y
+  ret i16 %z
+}
+
+define i16 @main(i16 %x) #0 {
+; CHECK-LABEL: main:
+; CHECK:       # %bb.0: # %entry
+; CHECK-NEXT:    lpad 0
+; CHECK-NEXT:    tail OUTLINED_FUNCTION_0
+entry:
+  %y = add i16 5, %x
+  %z = mul i16 4, %y
+  ret i16 %z
+}
+
+attributes #0 = { minsize }
+
+!llvm.module.flags = !{!0, !1}
+
+!0 = !{i32 8, !"cf-protection-branch", i32 1}
+!1 = !{i32 1, !"cf-branch-label-scheme", !"unlabeled"}