[AArch64] Make sure XRay pseudo-instruction sizes are reported correctly

[duck-37]

Summary

AArch64InstrInfo::getInstSizeInBytes does not take XRay instrumentation opcodes into account.
The default case of this function unconditionally returns 4, except for size definitions specified by TableGen.
However, on AArch64, the XRay pseudo-instructions expand to 32 bytes.
Since the XRay pseudo-opcodes are target-independent, the TableGen path doesn't get hit and therefore the size returned is wrong.

Fixes https://github.com/llvm/llvm-project/issues/52712

[duck-37]

Add newline to end of test case

[duck-37]

Okay, taking this off the review queue until I take a look at the other bug incidentally exposed by fixing this one; the MachineOutliner doesn't properly adjust attributes of new outlined functions with XRay instrumentation opcodes. (should it even run on those at all?)
As such, what happens is that this check doesn't pass, meaning CurrentFnBegin isn't set, meaning that an assertion failure is thrown when the code generator tries to use it as a symbol when emitting the XRay instrumentation table.
The reason this testcase didn't fail before is because AArch64InstrInfo::getOutliningCandidateInfo uses the sizes of instructions as part of the outlining heuristic. When the pseudo-opcode sizes were fixed, the heuristic decided it was profitable to outline an XRay pseudo-instruction, triggering the bug.

[duck-37]

This comment was removed by duck-37.

[zjaffal]

This comment was removed by zjaffal.

[duck-37]

Also addressed by D147982.

llvm/lib/Target/AArch64/AArch64InstrInfo.cpp

case TargetOpcode::PATCHPOINT:
     break;
   case TargetOpcode::STATEPOINT:
     NumBytes = StatepointOpers(&MI).getNumPatchBytes();
     assert(NumBytes % 4 == 0 && "Invalid number of NOP bytes requested!");
     // No patch bytes means a normal call inst is emitted
     if (NumBytes == 0)
       NumBytes = 4;
     break;
+  case TargetOpcode::PATCHABLE_FUNCTION_ENTER:
+  case TargetOpcode::PATCHABLE_FUNCTION_EXIT:
+  case TargetOpcode::PATCHABLE_TAIL_CALL:
+    // These pseudo-instructions resolve to 32 bytes of padding at runtime;
+    // 4 bytes for a branch over 28 bytes of NOPs.
+    NumBytes = 32;
+    break;
   case AArch64::SPACE:
     NumBytes = MI.getOperand(1).getImm();
     break;
   case TargetOpcode::BUNDLE:
     NumBytes = getInstBundleLength(MI);
     break;
   }
 

llvm/test/CodeGen/AArch64/xray-jump-table-compression.ll

+; RUN: llc -O3 -mtriple=aarch64-unknown-linux-gnu < %s | FileCheck %s
+
+; jump table compression to incorrectly downsizes label offsets here if xray instructions aren't taken into account
+define dso_local noundef i32 @foo(i32 noundef %0) "function-instrument"="xray-always" {
+; CHECK-LABEL: foo:
+  %2 = alloca i32, align 4
+  switch i32 %0, label %3 [
+    i32 1, label %3
+    i32 2, label %4
+    i32 3, label %5
+    i32 4, label %6
+    i32 5, label %7
+    i32 6, label %8
+    i32 7, label %9
+    i32 8, label %10
+    i32 9, label %11
+    i32 10, label %12
+    i32 11, label %13
+    i32 12, label %14
+    i32 13, label %15
+    i32 14, label %16
+    i32 15, label %17
+    i32 16, label %18
+    i32 17, label %19
+    i32 18, label %20
+    i32 19, label %21
+    i32 20, label %22
+    i32 21, label %23
+    i32 22, label %24
+    i32 23, label %25
+  ]
+
+3:                                                ; preds = %1
+; CHECK-LABEL: LBB0_2:
+  store volatile i32 1, ptr %2, align 4
+  ret i32 333
+
+4:                                                ; preds = %1
+  store volatile i32 2, ptr %2, align 4
+  ret i32 333
+
+5:                                                ; preds = %1
+  store volatile i32 3, ptr %2, align 4
+  ret i32 333
+
+6:                                                ; preds = %1
+  store volatile i32 4, ptr %2, align 4
+  ret i32 333
+
+7:                                                ; preds = %1
+  store volatile i32 5, ptr %2, align 4
+  ret i32 333
+
+8:                                                ; preds = %1
+  store volatile i32 6, ptr %2, align 4
+  ret i32 333
+
+9:                                                ; preds = %1
+  store volatile i32 7, ptr %2, align 4
+  ret i32 333
+
+10:                                               ; preds = %1
+  store volatile i32 8, ptr %2, align 4
+  ret i32 333
+
+11:                                               ; preds = %1
+  store volatile i32 9, ptr %2, align 4
+  ret i32 333
+
+12:                                               ; preds = %1
+  store volatile i32 10, ptr %2, align 4
+  ret i32 333
+
+13:                                               ; preds = %1
+  store volatile i32 11, ptr %2, align 4
+  ret i32 333
+
+14:                                               ; preds = %1
+  store volatile i32 12, ptr %2, align 4
+  ret i32 333
+
+15:                                               ; preds = %1
+  store volatile i32 13, ptr %2, align 4
+  ret i32 333
+
+16:                                               ; preds = %1
+  store volatile i32 14, ptr %2, align 4
+  ret i32 333
+
+17:                                               ; preds = %1
+  store volatile i32 15, ptr %2, align 4
+  ret i32 333
+
+18:                                               ; preds = %1
+  store volatile i32 16, ptr %2, align 4
+  ret i32 333
+
+19:                                               ; preds = %1
+  store volatile i32 17, ptr %2, align 4
+  ret i32 333
+
+20:                                               ; preds = %1
+  store volatile i32 18, ptr %2, align 4
+  ret i32 333
+
+21:                                               ; preds = %1
+  store volatile i32 19, ptr %2, align 4
+  ret i32 333
+
+22:                                               ; preds = %1
+  store volatile i32 20, ptr %2, align 4
+  ret i32 333
+
+23:                                               ; preds = %1
+  store volatile i32 21, ptr %2, align 4
+  ret i32 333
+
+24:                                               ; preds = %1
+  store volatile i32 22, ptr %2, align 4
+  ret i32 333
+
+25:                                               ; preds = %1
+  store volatile i32 23, ptr %2, align 4
+  ret i32 333
+}
+
+; CHECK-NOT:  .byte  (.LBB0_2-.LBB0_2)>>2