[SPARC] Prevent meta instructions from being inserted into delay slots (#161111)

Do not move meta instructions like `FAKE_USE`/`@llvm.fake.use` into
delay slots, as they don't correspond to real machine instructions.

This should fix crashes when compiling with, for example, `clang -Og`.

Author: koachan

llvm/lib/Target/Sparc/DelaySlotFiller.cpp

@@ -206,8 +206,8 @@ Filler::findDelayInstr(MachineBasicBlock &MBB,
     if (!done)
       --I;
 
-    // skip debug instruction
-    if (I->isDebugInstr())
+    // Skip meta instructions.
+    if (I->isMetaInstruction())
       continue;
 
     if (I->hasUnmodeledSideEffects() || I->isInlineAsm() || I->isPosition() ||

llvm/test/CodeGen/SPARC/2011-01-19-DelaySlot.ll

@@ -184,4 +184,29 @@ entry:
   ret i32 %2
 }
 
+define i32 @test_generic_inst(i32 %arg) #0 {
+;CHECK-LABEL: test_generic_inst:
+;CHECK: ! fake_use: {{.*}}
+;CHECK: bne {{.*}}
+;CHECK-NEXT: nop
+  %bar1 = call i32 @bar(i32 %arg)
+  %even = and i32 %bar1, 1
+  %cmp = icmp eq i32 %even, 0
+  ; This shouldn't get reordered into a delay slot
+  call void (...) @llvm.fake.use(i32 %arg)
+  br i1 %cmp, label %true, label %false
+true:
+  %bar2 = call i32 @bar(i32 %bar1)
+  br label %cont
+
+false:
+  %inc = add nsw i32 %bar1, 1
+  br label %cont
+
+cont:
+  %ret = phi i32 [ %bar2, %true ], [ %inc, %false ]
+  ret i32 %ret
+}
+
+declare void @llvm.fake.use(...)
 attributes #0 = { nounwind "disable-tail-calls"="true" }