llvm-6502/test/CodeGen/ARM/indirectbr-3.ll
Lang Hames 7b61a70193 Refactor AnalyzeBranch on ARM. The previous version did not always analyze
indirect branches correctly. Under some circumstances, this led to the deletion
of basic blocks that were the destination of indirect branches. In that case it
left indirect branches to nowhere in the code.

This patch replaces, and is more general than either of the previous fixes for
indirect-branch-analysis issues, r181161 and r186461.

For other branches (not indirect) this refactor should have *almost* identical
behavior to the previous version. There are some corner cases where this
refactor is able to analyze blocks that the previous version could not (e.g.
this necessitated the update to thumb2-ifcvt2.ll). 

<rdar://problem/14464830>



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@186735 91177308-0d34-0410-b5e6-96231b3b80d8
2013-07-19 23:52:47 +00:00

33 lines
870 B
LLVM

; RUN: llc < %s -mtriple=thumbv7-apple-ios | FileCheck %s
; If ARMBaseInstrInfo::AnalyzeBlocks returns the wrong value, which was possible
; for blocks with indirect branches, the IfConverter could end up deleting
; blocks that were the destinations of indirect branches, leaving branches to
; nowhere.
; <rdar://problem/14464830>
define i32 @preserve_blocks(i32 %x) {
; preserve_blocks:
; CHECK: Block address taken
; CHECK: movs r0, #2
; CHECK: movs r0, #1
; CHECK-NOT: Address of block that was removed by CodeGen
entry:
%c2 = icmp slt i32 %x, 3
%blockaddr = select i1 %c2, i8* blockaddress(@preserve_blocks, %ibt1), i8* blockaddress(@preserve_blocks, %ibt2)
%c1 = icmp eq i32 %x, 0
br i1 %c1, label %pre_ib, label %nextblock
nextblock:
ret i32 3
ibt1:
ret i32 2
ibt2:
ret i32 1
pre_ib:
indirectbr i8* %blockaddr, [ label %ibt1, label %ibt2 ]
}