Insert denominator zero checks for NaCl

test/NaCl/ARM/divrem-guards.ll

+; RUN: opt < %s -insert-divide-check -S | FileCheck -check-prefix=OPT %s
+; RUN: llc -mtriple=armv7-unknown-nacl -sfi-branch -filetype=obj %s -o - \
+; RUN:  | llvm-objdump -disassemble -triple armv7 -mattr=+nacl-trap - \
+; RUN:  | FileCheck -check-prefix=ARM %s
+
+
+; Check for all four operators that need guards.
+define i32 @mysdiv(i32 %x, i32 %y) #0 {
+entry:
+  %div1 = sdiv i32 %x, %y
+; OPT: %0 = icmp eq i32 %y, 0
+; OPT-NEXT: br i1 %0, label %divrem.by.zero, label %guarded.divrem
+; OPT: guarded.divrem:
+; OPT-NEXT: sdiv
+; OPT-NEXT: ret
+; OPT: divrem.by.zero:
+; OPT-NEXT: call void @llvm.trap()
+; OPT-NEXT: unreachable
+; ARM: cmp r1, #0
+; ARM-NEXT: beq
+  ret i32 %div1
+; ARM: f0 de fe e7
+}
+
+define i32 @myudiv(i32 %x, i32 %y) #0 {
+entry:
+  %div1 = udiv i32 %x, %y
+; OPT: %0 = icmp eq i32 %y, 0
+; OPT-NEXT: br i1 %0, label %divrem.by.zero, label %guarded.divrem
+; OPT: guarded.divrem:
+; OPT-NEXT: udiv
+; OPT-NEXT: ret
+; OPT: divrem.by.zero:
+; OPT-NEXT: call void @llvm.trap()
+; OPT-NEXT: unreachable
+; ARM: cmp r1, #0
+; ARM-NEXT: beq
+  ret i32 %div1
+; ARM: f0 de fe e7
+}
+
+define i32 @mysrem(i32 %x, i32 %y) #0 {
+entry:
+  %rem1 = srem i32 %x, %y
+; OPT: %0 = icmp eq i32 %y, 0
+; OPT-NEXT: br i1 %0, label %divrem.by.zero, label %guarded.divrem
+; OPT: guarded.divrem:
+; OPT-NEXT: srem
+; OPT-NEXT: ret
+; OPT: divrem.by.zero:
+; OPT-NEXT: call void @llvm.trap()
+; OPT-NEXT: unreachable
+; ARM: cmp r1, #0
+; ARM-NEXT: beq
+  ret i32 %rem1
+; ARM: f0 de fe e7
+}
+
+define i32 @myurem(i32 %x, i32 %y) #0 {
+entry:
+  %rem1 = urem i32 %x, %y
+; OPT: %0 = icmp eq i32 %y, 0
+; OPT-NEXT: br i1 %0, label %divrem.by.zero, label %guarded.divrem
+; OPT: guarded.divrem:
+; OPT-NEXT: urem
+; OPT-NEXT: ret
+; OPT: divrem.by.zero:
+; OPT-NEXT: call void @llvm.trap()
+; OPT-NEXT: unreachable
+; ARM: cmp r1, #0
+; ARM-NEXT: beq
+  ret i32 %rem1
+; ARM: f0 de fe e7
+}
+
+; Divides by non-zero constants should not be guarded.
+define i32 @mysdiv_const(i32 %x) #0 {
+entry:
+  %div1 = sdiv i32 %x, 10
+; OPT-NOT: icmp
+; OPT-NOT: br
+; OPT-NOT: guarded.divrem:
+; OPT-NOT: divrem.by.zero:
+; OPT-NOT: call void @llvm.trap()
+; OPT-NOT: unreachable
+; ARM-NOT: cmp r1, #0
+; ARM-NOT: f0 de fe e7
+  ret i32 %div1
+}
+
+; Divides by explicit zero should prefixed by a trap.
+define i32 @mysdiv_zero(i32 %x) #0 {
+entry:
+  %div1 = sdiv i32 %x, 0
+; OPT-NOT: guarded.divrem:
+; OPT-NOT: divrem.by.zero:
+; OPT: call void @llvm.trap()
+; OPT-NEXT: sdiv
+; ARM-NOT: cmp r1, #0
+; ARM: f0 de fe e7
+  ret i32 %div1
+}
+
+attributes #0 = { nounwind }