maxjhandsome
/
llvm-project
forked from OSchip/llvm-project
1
0
Fork 0
Code Issues Pull Requests Packages Releases Wiki Activity
llvm-project/llvm/test/CodeGen/ARM/indirectbr-3.ll

41 lines
1.3 KiB
LLVM
Raw Normal View History

IfConversion: Rescan diamonds. The cost of predicating a diamond is only the instructions that are not shared between the two branches. Additionally If a predicate clobbering instruction occurs in the shared portion of the branches (e.g. a cond move), it may still be possible to if convert the sub-cfg. This change handles these two facts by rescanning the non-shared portion of a diamond sub-cfg to recalculate both the predication cost and whether both blocks are pred-clobbering. Fixed 2 bugs before recommitting. Branch instructions must be compared and found identical before diamond conversion. Also, predicate-clobbering instructions in the shared prefix disqualifies a potential diamond conversion. Includes tests for both. llvm-svn: 279670
2016-08-25 05:34:24 +08:00
; RUN: llc < %s -mtriple=thumbv7-apple-ios -arm-atomic-cfg-tidy=0 -stats 2>&1 | FileCheck %s
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> llvm-svn: 186735
2013-07-20 07:52:47 +08:00
; 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, #1
IfConversion: Rescan diamonds. The cost of predicating a diamond is only the instructions that are not shared between the two branches. Additionally If a predicate clobbering instruction occurs in the shared portion of the branches (e.g. a cond move), it may still be possible to if convert the sub-cfg. This change handles these two facts by rescanning the non-shared portion of a diamond sub-cfg to recalculate both the predication cost and whether both blocks are pred-clobbering. Fixed 2 bugs before recommitting. Branch instructions must be compared and found identical before diamond conversion. Also, predicate-clobbering instructions in the shared prefix disqualifies a potential diamond conversion. Includes tests for both. llvm-svn: 279670
2016-08-25 05:34:24 +08:00
; CHECK: Block address taken
; CHECK: movs r0, #2
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> llvm-svn: 186735
2013-07-20 07:52:47 +08:00
; CHECK-NOT: Address of block that was removed by CodeGen
IfConversion: Rescan diamonds. The cost of predicating a diamond is only the instructions that are not shared between the two branches. Additionally If a predicate clobbering instruction occurs in the shared portion of the branches (e.g. a cond move), it may still be possible to if convert the sub-cfg. This change handles these two facts by rescanning the non-shared portion of a diamond sub-cfg to recalculate both the predication cost and whether both blocks are pred-clobbering. Fixed 2 bugs before recommitting. Branch instructions must be compared and found identical before diamond conversion. Also, predicate-clobbering instructions in the shared prefix disqualifies a potential diamond conversion. Includes tests for both. llvm-svn: 279670
2016-08-25 05:34:24 +08:00
; Separate bug. There are no valid diamonds to if-convert in this file.
; There was a bug in the if-conversion code that would if-convert a false
; diamond where one side had a return and the other had an indirect branch.
; Make sure no diamond conversions occurred while compiling this file.
; CHECK: Statistics Collected
; CHECK-NOT: 1 ifcvt - Number of diamond if-conversions performed
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> llvm-svn: 186735
2013-07-20 07:52:47 +08:00
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 ]
}