From c22960dba6583c3044d37c3d8b411f393cba46e0 Mon Sep 17 00:00:00 2001 From: Tim Northover Date: Tue, 17 Jun 2014 11:31:42 +0000 Subject: AArch64: estimate inline asm length during branch relaxation To make sure branches are in range, we need to do a better job of estimating the length of an inline assembly block than "it's probably 1 instruction, who'd write asm with more than that?". Fortunately there's already a (highly suspect, see how many ways you can think of to break it!) callback for this purpose, which is used by the other targets. rdar://problem/17277590 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@211095 91177308-0d34-0410-b5e6-96231b3b80d8 --- test/CodeGen/AArch64/branch-relax-asm.ll | 35 ++++++++++++++++++++++++++++++++ 1 file changed, 35 insertions(+) create mode 100644 test/CodeGen/AArch64/branch-relax-asm.ll (limited to 'test') diff --git a/test/CodeGen/AArch64/branch-relax-asm.ll b/test/CodeGen/AArch64/branch-relax-asm.ll new file mode 100644 index 0000000000..7409c84e61 --- /dev/null +++ b/test/CodeGen/AArch64/branch-relax-asm.ll @@ -0,0 +1,35 @@ +; RUN: llc -mtriple=aarch64-apple-ios7.0 -disable-block-placement -aarch64-tbz-offset-bits=4 -o - %s | FileCheck %s +define i32 @test_asm_length(i32 %in) { +; CHECK-LABEL: test_asm_length: + + ; It would be more natural to use just one "tbnz %false" here, but if the + ; number of instructions in the asm is counted reasonably, that block is out + ; of the limited range we gave tbz. So branch relaxation has to invert the + ; condition. +; CHECK: tbz w0, #0, [[TRUE:LBB[0-9]+_[0-9]+]] +; CHECK: b [[FALSE:LBB[0-9]+_[0-9]+]] + +; CHECK: [[TRUE]]: +; CHECK: orr w0, wzr, #0x4 +; CHECK: nop +; CHECK: nop +; CHECK: nop +; CHECK: nop +; CHECK: nop +; CHECK: nop +; CHECK: ret + +; CHECK: [[FALSE]]: +; CHECK: ret + + %val = and i32 %in, 1 + %tst = icmp eq i32 %val, 0 + br i1 %tst, label %true, label %false + +true: + call void asm sideeffect "nop\0A\09nop\0A\09nop\0A\09nop\0A\09nop\0A\09nop", ""() + ret i32 4 + +false: + ret i32 0 +} -- cgit v1.2.3