add mir test

Author: ellishg

llvm/lib/CodeGen/MachineOutliner.cpp

@@ -1076,22 +1076,17 @@ bool MachineOutliner::outline(
                       << " B) > threshold (" << OutlinerBenefitThreshold
                       << " B)\n");
 
-    // Remove all Linker Optimization Hints from the candidates since we did not
-    // check if the set of hints are the same for each of them.
+    // Remove all Linker Optimization Hints from the candidates.
     // TODO: The intersection of the LOHs from all candidates should be legal in
     // the outlined function.
     SmallPtrSet<MachineInstr *, 2> MIs;
-    std::optional<size_t> MinRemovedLOHs;
     for (Candidate &C : OF->Candidates) {
       const TargetInstrInfo &TII = *C.getMF()->getSubtarget().getInstrInfo();
       for (MachineInstr &MI : C)
         MIs.insert(&MI);
-      size_t NumRemoved = TII.clearLinkerOptimizationHints(MIs);
+      NumRemovedLOHs += TII.clearLinkerOptimizationHints(MIs);
       MIs.clear();
-      MinRemovedLOHs =
-          std::min(MinRemovedLOHs.value_or(NumRemoved), NumRemoved);
     }
-    NumRemovedLOHs += MinRemovedLOHs.value_or(0);
 
     // It's beneficial. Create the function and outline its sequence's
     // occurrences.

llvm/test/CodeGen/AArch64/machine-outliner-loh.mir

@@ -0,0 +1,50 @@
+# RUN: llc %s -mtriple=aarch64-apple-ios -run-pass=aarch64-collect-loh -run-pass=machine-outliner -stats -o - 2>%t | FileCheck %s
+# RUN: FileCheck %s --input-file=%t --check-prefix=STATS
+# REQUIRES: asserts
+
+--- |
+  define void  @func0() noredzone minsize { ret void }
+
+  @g0 = external global i32
+...
+---
+# CHECK-LABEL: name: func0
+name: func0
+tracksRegLiveness: true
+body: |
+  ; CHECK-LABEL: bb.0:
+  bb.0:
+    ; CHECK: BL @OUTLINED_FUNCTION_0
+    $x10 = ADRP target-flags(aarch64-page) @g0
+    $x11 = ADDXri $x10, target-flags(aarch64-pageoff) @g0, 0
+    $w0 = ORRWri $wzr, 1
+    $w0 = ORRWri $wzr, 1
+    $w0 = ORRWri $wzr, 1
+    $w0 = ORRWri $wzr, 1
+
+  ; CHECK-LABEL: bb.1:
+  bb.1:
+    ; CHECK: BL @OUTLINED_FUNCTION_0
+    ; MCLOH_AdrpAdd is not generated because $x11 is still live. If we want to
+    ; outline these instructions, we must remove the MCLOH_AdrpAdd from bb.0.
+    $x10 = ADRP target-flags(aarch64-page) @g0
+    $x11 = ADDXri $x10, target-flags(aarch64-pageoff) @g0, 0
+    $w0 = ORRWri $wzr, 1
+    $w0 = ORRWri $wzr, 1
+    $w0 = ORRWri $wzr, 1
+    $w0 = ORRWri $wzr, 1
+    ; CHECK: $x12 = ADDXri $x11, target-flags(aarch64-pageoff) @g0, 0
+    $x12 = ADDXri $x11, target-flags(aarch64-pageoff) @g0, 0
+
+...
+
+# CHECK-LABEL: name: OUTLINED_FUNCTION_0
+# CHECK:           $x10 = ADRP target-flags(aarch64-page) @g0
+# CHECK:           $x11 = ADDXri $x10, target-flags(aarch64-pageoff) @g0, 0
+# CHECK:           $w0 = ORRWri $wzr, 1
+# CHECK:           $w0 = ORRWri $wzr, 1
+# CHECK:           $w0 = ORRWri $wzr, 1
+# CHECK:           $w0 = ORRWri $wzr, 1
+
+# STATS: 1 aarch64-collect-loh - Number of simplifiable ADRP + ADD
+# STATS: 1 machine-outliner    - Total number of Linker Optimization Hints removed