[ImplicitNullChecks] Be smarter in picking the memory op.
Summary:
Before this change ImplicitNullChecks would only pick loads of the form:
```
test Reg, Reg
jz elsewhere
fallthrough:
movl 32(Reg), Reg2
```
but not (say)
```
test Reg, Reg
jz elsewhere
fallthrough:
inc Reg3
movl 32(Reg), Reg2
```
This change teaches ImplicitNullChecks to look through "unrelated"
instructions like `inc Reg3` when searching for a load instruction
to convert to a trapping load.
Reviewers: atrick, JosephTremoulet, reames
Subscribers: llvm-commits
Differential Revision: http://reviews.llvm.org/D11044
llvm-svn: 241850
diff --git a/llvm/test/CodeGen/X86/implicit-null-check.ll b/llvm/test/CodeGen/X86/implicit-null-check.ll
index 1d1b36b..fd7a902 100644
--- a/llvm/test/CodeGen/X86/implicit-null-check.ll
+++ b/llvm/test/CodeGen/X86/implicit-null-check.ll
@@ -76,6 +76,31 @@
ret i32 %p1
}
+define i32 @imp_null_check_hoist_over_unrelated_load(i32* %x, i32* %y, i32* %z) {
+; CHECK-LABEL: _imp_null_check_hoist_over_unrelated_load:
+; CHECK: Ltmp7:
+; CHECK: movl (%rdi), %eax
+; CHECK: movl (%rsi), %ecx
+; CHECK: movl %ecx, (%rdx)
+; CHECK: retq
+; CHECK: Ltmp6:
+; 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:
+ %t0 = load i32, i32* %y
+ %t1 = load i32, i32* %x
+ store i32 %t0, i32* %z
+ ret i32 %t1
+}
+
!0 = !{}
; CHECK-LABEL: __LLVM_FaultMaps:
@@ -88,7 +113,7 @@
; CHECK-NEXT: .short 0
; # functions:
-; CHECK-NEXT: .long 3
+; CHECK-NEXT: .long 4
; FunctionAddr:
; CHECK-NEXT: .quad _imp_null_check_add_result
@@ -117,6 +142,19 @@
; CHECK-NEXT: .long Ltmp2-_imp_null_check_gep_load
; FunctionAddr:
+; CHECK-NEXT: .quad _imp_null_check_hoist_over_unrelated_load
+; NumFaultingPCs
+; CHECK-NEXT: .long 1
+; Reserved:
+; CHECK-NEXT: .long 0
+; Fault[0].Type:
+; CHECK-NEXT: .long 1
+; Fault[0].FaultOffset:
+; CHECK-NEXT: .long Ltmp7-_imp_null_check_hoist_over_unrelated_load
+; Fault[0].HandlerOffset:
+; CHECK-NEXT: .long Ltmp6-_imp_null_check_hoist_over_unrelated_load
+
+; FunctionAddr:
; CHECK-NEXT: .quad _imp_null_check_load
; NumFaultingPCs
; CHECK-NEXT: .long 1
@@ -131,10 +169,12 @@
; OBJDUMP: FaultMap table:
; OBJDUMP-NEXT: Version: 0x1
-; OBJDUMP-NEXT: NumFunctions: 3
+; OBJDUMP-NEXT: NumFunctions: 4
; 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: 7
+; OBJDUMP-NEXT: FunctionAddress: 0x000000, NumFaultingPCs: 1
; OBJDUMP-NEXT: Fault kind: FaultingLoad, faulting PC offset: 0, handling PC offset: 3