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| author | James Molloy <james.molloy@arm.com> | 2016-09-09 12:52:24 +0000 |
|---|---|---|
| committer | James Molloy <james.molloy@arm.com> | 2016-09-09 12:52:24 +0000 |
| commit | 4d86bed0bb2d109f9aa802cc09377900b84c09bb (patch) | |
| tree | 19d55765b086baec9f875b689c46d4006c30bd9a /llvm/test/CodeGen/Thumb/cmp-add-fold.ll | |
| parent | a6987a4dddc61168fbccba7493c176d35689a004 (diff) | |
| download | bcm5719-llvm-4d86bed0bb2d109f9aa802cc09377900b84c09bb.tar.gz bcm5719-llvm-4d86bed0bb2d109f9aa802cc09377900b84c09bb.zip | |
[Thumb] Select (CMPZ X, -C) -> (CMPZ (ADDS X, C), 0)
The CMPZ #0 disappears during peepholing, leaving just a tADDi3, tADDi8 or t2ADDri. This avoids having to materialize the expensive negative constant in Thumb-1, and allows a shrinking from a 32-bit CMN to a 16-bit ADDS in Thumb-2.
llvm-svn: 281040
Diffstat (limited to 'llvm/test/CodeGen/Thumb/cmp-add-fold.ll')
| -rw-r--r-- | llvm/test/CodeGen/Thumb/cmp-add-fold.ll | 32 |
1 files changed, 32 insertions, 0 deletions
diff --git a/llvm/test/CodeGen/Thumb/cmp-add-fold.ll b/llvm/test/CodeGen/Thumb/cmp-add-fold.ll new file mode 100644 index 00000000000..b0ad8ab93f8 --- /dev/null +++ b/llvm/test/CodeGen/Thumb/cmp-add-fold.ll @@ -0,0 +1,32 @@ +; RUN: llc -mtriple=thumbv6m-eabi -verify-machineinstrs < %s | FileCheck --check-prefix=CHECK --check-prefix=T1 %s +; RUN: llc -mtriple=thumbv7m-eabi -verify-machineinstrs < %s | FileCheck --check-prefix=CHECK --check-prefix=T2 %s + +; CHECK-LABEL: addri1: +; CHECK: adds r0, #3 +; T1-NEXT: b{{eq|ne}} +; T2-NOT: cmp +define i32 @addri1(i32 %a, i32 %b) { + %c = add i32 %a, 3 + %d = icmp eq i32 %c, 0 + br i1 %d, label %true, label %false + +true: + ret i32 4 +false: + ret i32 5 +} + +; CHECK-LABEL: addri2: +; CHECK: adds r0, #254 +; T1-NEXT: b{{eq|ne}} +; T2-NOT: cmp +define i32 @addri2(i32 %a, i32 %b) { + %c = add i32 %a, 254 + %d = icmp eq i32 %c, 0 + br i1 %d, label %true, label %false + +true: + ret i32 4 +false: + ret i32 5 +} |
