[PATCH] D29120: [ImplicitNullCheck] Extend canReorder scope

[Serguei Katkov via Phabricator via llvm-commits]

skatkov created this revision.

This change allows a re-order of two intructions if their uses
are overlapped.


https://reviews.llvm.org/D29120

Files:
  lib/CodeGen/ImplicitNullChecks.cpp
  test/CodeGen/X86/implicit-null-check.ll


Index: test/CodeGen/X86/implicit-null-check.ll
===================================================================
--- test/CodeGen/X86/implicit-null-check.ll
+++ test/CodeGen/X86/implicit-null-check.ll
@@ -135,6 +135,33 @@
   ret i32 200
 }
 
+define i32 @imp_null_check_gep_load_with_use_dep(i32* %x, i32 %a) {
+; CHECK-LABEL: imp_null_check_gep_load_with_use_dep:
+; CHECK: [[BB0_imp_null_check_gep_load_with_use_dep:L[^:]+]]:
+; CHECK: movl (%rdi), %eax
+; CHECK: addl %edi, %esi
+; CHECK: leal 4(%rax,%rsi), %eax
+; CHECK: retq
+; CHECK: [[BB1_imp_null_check_gep_load_with_use_dep:LBB5_[0-9]+]]:
+; CHECK: movl $42, %eax
+; CHECK: retq
+
+ entry:
+  %c = icmp eq i32* %x, null
+  br i1 %c, label %is_null, label %not_null, !make.implicit !0
+
+ is_null:
+  ret i32 42
+
+ not_null:
+  %x.loc = getelementptr i32, i32* %x, i32 1
+  %y = ptrtoint i32* %x.loc to i32
+  %b = add i32 %a, %y
+  %t = load i32, i32* %x
+  %z = add i32 %t, %b
+  ret i32 %z
+}
+
 !0 = !{}
 
 ; CHECK-LABEL: __LLVM_FaultMaps:
@@ -147,7 +174,7 @@
 ; CHECK-NEXT: .short 0
 
 ; # functions:
-; CHECK-NEXT: .long 5
+; CHECK-NEXT: .long 6
 
 ; FunctionAddr:
 ; CHECK-NEXT: .quad _imp_null_check_add_result
@@ -176,6 +203,19 @@
 ; CHECK-NEXT: .long [[BB1_imp_null_check_gep_load]]-_imp_null_check_gep_load
 
 ; FunctionAddr:
+; CHECK-NEXT: .quad _imp_null_check_gep_load_with_use_dep
+; NumFaultingPCs
+; CHECK-NEXT: .long 1
+; Reserved:
+; CHECK-NEXT: .long 0
+; Fault[0].Type:
+; CHECK-NEXT: .long 1
+; Fault[0].FaultOffset:
+; CHECK-NEXT: .long [[BB0_imp_null_check_gep_load_with_use_dep]]-_imp_null_check_gep_load_with_use_dep
+; Fault[0].HandlerOffset:
+; CHECK-NEXT: .long [[BB1_imp_null_check_gep_load_with_use_dep]]-_imp_null_check_gep_load_with_use_dep
+
+; FunctionAddr:
 ; CHECK-NEXT: .quad _imp_null_check_hoist_over_unrelated_load
 ; NumFaultingPCs
 ; CHECK-NEXT: .long 1
@@ -216,12 +256,14 @@
 
 ; OBJDUMP: FaultMap table:
 ; OBJDUMP-NEXT: Version: 0x1
-; OBJDUMP-NEXT: NumFunctions: 5
+; OBJDUMP-NEXT: NumFunctions: 6
 ; OBJDUMP-NEXT: FunctionAddress: 0x000000, NumFaultingPCs: 1
 ; OBJDUMP-NEXT: Fault kind: FaultingLoad, faulting PC offset: 0, handling PC offset: 5
 ; OBJDUMP-NEXT: FunctionAddress: 0x000000, NumFaultingPCs: 1
 ; OBJDUMP-NEXT: Fault kind: FaultingLoad, faulting PC offset: 0, handling PC offset: 7
 ; OBJDUMP-NEXT: FunctionAddress: 0x000000, NumFaultingPCs: 1
+; OBJDUMP-NEXT: Fault kind: FaultingLoad, faulting PC offset: 0, handling PC offset: 9
+; OBJDUMP-NEXT: FunctionAddress: 0x000000, NumFaultingPCs: 1
 ; OBJDUMP-NEXT: Fault kind: FaultingLoad, faulting PC offset: 0, handling PC offset: 7
 ; OBJDUMP-NEXT: FunctionAddress: 0x000000, NumFaultingPCs: 1
 ; OBJDUMP-NEXT: Fault kind: FaultingLoad, faulting PC offset: 0, handling PC offset: 3
Index: lib/CodeGen/ImplicitNullChecks.cpp
===================================================================
--- lib/CodeGen/ImplicitNullChecks.cpp
+++ lib/CodeGen/ImplicitNullChecks.cpp
@@ -248,7 +248,7 @@
 
       unsigned RegB = MOB.getReg();
 
-      if (TRI->regsOverlap(RegA, RegB))
+      if (TRI->regsOverlap(RegA, RegB) && (MOA.isDef() || MOB.isDef()))
         return false;
     }
   }


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