| ; RUN: llc -mtriple=x86_64-apple-macosx -O3 -debug-only=faultmaps -enable-implicit-null-checks < %s 2>&1 | FileCheck %s |
| ; REQUIRES: asserts |
| |
| ; List cases where we should *not* be emitting implicit null checks. |
| |
| ; CHECK-NOT: Fault Map Output |
| |
| define i32 @imp_null_check_load(i32* %x, i32* %y) { |
| entry: |
| %c = icmp eq i32* %x, null |
| ; It isn't legal to move the load from %x from "not_null" to here -- |
| ; the store to %y could be aliasing it. |
| br i1 %c, label %is_null, label %not_null, !make.implicit !0 |
| |
| is_null: |
| ret i32 42 |
| |
| not_null: |
| store i32 0, i32* %y |
| %t = load i32, i32* %x |
| ret i32 %t |
| } |
| |
| define i32 @imp_null_check_gep_load(i32* %x) { |
| 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: |
| ; null + 5000 * sizeof(i32) lies outside the null page and hence the |
| ; load to %t cannot be assumed to be reliably faulting. |
| %x.gep = getelementptr i32, i32* %x, i32 5000 |
| %t = load i32, i32* %x.gep |
| ret i32 %t |
| } |
| |
| define i32 @imp_null_check_neg_gep_load(i32* %x) { |
| 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: |
| ; null - 5000 * sizeof(i32) lies outside the null page and hence the |
| ; load to %t cannot be assumed to be reliably faulting. |
| %x.gep = getelementptr i32, i32* %x, i32 -5000 |
| %t = load i32, i32* %x.gep |
| ret i32 %t |
| } |
| |
| define i32 @imp_null_check_load_no_md(i32* %x) { |
| ; This is fine, except it is missing the !make.implicit metadata. |
| entry: |
| %c = icmp eq i32* %x, null |
| br i1 %c, label %is_null, label %not_null |
| |
| is_null: |
| ret i32 42 |
| |
| not_null: |
| %t = load i32, i32* %x |
| ret i32 %t |
| } |
| |
| define i32 @imp_null_check_no_hoist_over_acquire_load(i32* %x, i32* %y) { |
| ; We cannot hoist %t1 over %t0 since %t0 is an acquire load |
| 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 atomic i32, i32* %y acquire, align 4 |
| %t1 = load i32, i32* %x |
| %p = add i32 %t0, %t1 |
| ret i32 %p |
| } |
| |
| define i32 @imp_null_check_add_result(i32* %x, i32* %y) { |
| ; This will codegen to: |
| ; |
| ; movl (%rsi), %eax |
| ; addl (%rdi), %eax |
| ; |
| ; The load instruction we wish to hoist is the addl, but there is a |
| ; write-after-write hazard preventing that from happening. We could |
| ; get fancy here and exploit the commutativity of addition, but right |
| ; now -implicit-null-checks isn't that smart. |
| ; |
| |
| 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 |
| %p = add i32 %t0, %t1 |
| ret i32 %p |
| } |
| |
| ; This redefines the null check reg by doing a zero-extend, a shift on |
| ; itself and then an add. |
| ; Cannot be converted to implicit check since the zero reg is no longer zero. |
| define i64 @imp_null_check_load_shift_add_addr(i64* %x, i64 %r) { |
| entry: |
| %c = icmp eq i64* %x, null |
| br i1 %c, label %is_null, label %not_null, !make.implicit !0 |
| |
| is_null: |
| ret i64 42 |
| |
| not_null: |
| %y = ptrtoint i64* %x to i64 |
| %shry = shl i64 %y, 6 |
| %shry.add = add i64 %shry, %r |
| %y.ptr = inttoptr i64 %shry.add to i64* |
| %x.loc = getelementptr i64, i64* %y.ptr, i64 1 |
| %t = load i64, i64* %x.loc |
| ret i64 %t |
| } |
| |
| ; the memory op is not within faulting page. |
| define i64 @imp_null_check_load_addr_outside_faulting_page(i64* %x) { |
| entry: |
| %c = icmp eq i64* %x, null |
| br i1 %c, label %is_null, label %not_null, !make.implicit !0 |
| |
| is_null: |
| ret i64 42 |
| |
| not_null: |
| %y = ptrtoint i64* %x to i64 |
| %shry = shl i64 %y, 3 |
| %shry.add = add i64 %shry, 68719472640 |
| %y.ptr = inttoptr i64 %shry.add to i64* |
| %x.loc = getelementptr i64, i64* %y.ptr, i64 1 |
| %t = load i64, i64* %x.loc |
| ret i64 %t |
| } |
| |
| !0 = !{} |