| ; RUN: llc < %s -mtriple=thumbv7-apple-ios -mcpu=cortex-a8 | FileCheck %s |
| |
| ; ARM has a peephole optimization which looks for a def / use pair. The def |
| ; produces a 32-bit immediate which is consumed by the use. It tries to |
| ; fold the immediate by breaking it into two parts and fold them into the |
| ; immmediate fields of two uses. e.g |
| ; movw r2, #40885 |
| ; movt r3, #46540 |
| ; add r0, r0, r3 |
| ; => |
| ; add.w r0, r0, #3019898880 |
| ; add.w r0, r0, #30146560 |
| ; |
| ; However, this transformation is incorrect if the user produces a flag. e.g. |
| ; movw r2, #40885 |
| ; movt r3, #46540 |
| ; adds r0, r0, r3 |
| ; => |
| ; add.w r0, r0, #3019898880 |
| ; adds.w r0, r0, #30146560 |
| ; Note the adds.w may not set the carry flag even if the original sequence |
| ; would. |
| ; |
| ; rdar://11116189 |
| define i64 @t(i64 %aInput) nounwind { |
| ; CHECK-LABEL: t: |
| ; CHECK: movs [[REG:(r[0-9]+)]], #0 |
| ; CHECK: movt [[REG]], #46540 |
| ; CHECK: adds r{{[0-9]+}}, r{{[0-9]+}}, [[REG]] |
| %1 = mul i64 %aInput, 1000000 |
| %2 = add i64 %1, -7952618389194932224 |
| ret i64 %2 |
| } |