llvm-project/llvm/test/CodeGen/X86/ins_subreg_coalesce-1.ll

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; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
; RUN: llc < %s -mtriple=i686-- -mattr=-bmi | FileCheck %s
define fastcc i32 @t() nounwind {
; CHECK-LABEL: t:
Generalize MergeBlockIntoPredecessor. Replace uses of MergeBasicBlockIntoOnlyPred. Summary: Two utils methods have essentially the same functionality. This is an attempt to merge them into one. 1. lib/Transforms/Utils/Local.cpp : MergeBasicBlockIntoOnlyPred 2. lib/Transforms/Utils/BasicBlockUtils.cpp : MergeBlockIntoPredecessor Prior to the patch: 1. MergeBasicBlockIntoOnlyPred Updates either DomTree or DeferredDominance Moves all instructions from Pred to BB, deletes Pred Asserts BB has single predecessor If address was taken, replace the block address with constant 1 (?) 2. MergeBlockIntoPredecessor Updates DomTree, LoopInfo and MemoryDependenceResults Moves all instruction from BB to Pred, deletes BB Returns if doesn't have a single predecessor Returns if BB's address was taken After the patch: Method 2. MergeBlockIntoPredecessor is attempting to become the new default: Updates DomTree or DeferredDominance, and LoopInfo and MemoryDependenceResults Moves all instruction from BB to Pred, deletes BB Returns if doesn't have a single predecessor Returns if BB's address was taken Uses of MergeBasicBlockIntoOnlyPred that need to be replaced: 1. lib/Transforms/Scalar/LoopSimplifyCFG.cpp Updated in this patch. No challenges. 2. lib/CodeGen/CodeGenPrepare.cpp Updated in this patch. i. eliminateFallThrough is straightforward, but I added using a temporary array to avoid the iterator invalidation. ii. eliminateMostlyEmptyBlock(s) methods also now use a temporary array for blocks Some interesting aspects: - Since Pred is not deleted (BB is), the entry block does not need updating. - The entry block was being updated with the deleted block in eliminateMostlyEmptyBlock. Added assert to make obvious that BB=SinglePred. - isMergingEmptyBlockProfitable assumes BB is the one to be deleted. - eliminateMostlyEmptyBlock(BB) does not delete BB on one path, it deletes its unique predecessor instead. - adding some test owner as subscribers for the interesting tests modified: test/CodeGen/X86/avx-cmp.ll test/CodeGen/AMDGPU/nested-loop-conditions.ll test/CodeGen/AMDGPU/si-annotate-cf.ll test/CodeGen/X86/hoist-spill.ll test/CodeGen/X86/2006-11-17-IllegalMove.ll 3. lib/Transforms/Scalar/JumpThreading.cpp Not covered in this patch. It is the only use case using the DeferredDominance. I would defer to Brian Rzycki to make this replacement. Reviewers: chandlerc, spatel, davide, brzycki, bkramer, javed.absar Subscribers: qcolombet, sanjoy, nemanjai, nhaehnle, jlebar, tpr, kbarton, RKSimon, wmi, arsenm, llvm-commits Differential Revision: https://reviews.llvm.org/D48202 llvm-svn: 335183
2018-06-21 06:01:04 +08:00
; CHECK: # %bb.0: # %entry
; CHECK-NEXT: movzwl 0, %eax
; CHECK-NEXT: orl $2, %eax
; CHECK-NEXT: movw %ax, 0
; CHECK-NEXT: shrl $3, %eax
; CHECK-NEXT: andl $1, %eax
; CHECK-NEXT: retl
entry:
br i1 false, label %UnifiedReturnBlock, label %bb4
bb4: ; preds = %entry
br i1 false, label %bb17, label %bb22
bb17: ; preds = %bb4
ret i32 1
bb22: ; preds = %bb4
br i1 true, label %walkExprTree.exit, label %bb4.i
bb4.i: ; preds = %bb22
ret i32 0
walkExprTree.exit: ; preds = %bb22
%tmp83 = load i16, i16* null, align 4 ; <i16> [#uses=1]
%tmp84 = or i16 %tmp83, 2 ; <i16> [#uses=2]
store i16 %tmp84, i16* null, align 4
%tmp98993 = zext i16 %tmp84 to i32 ; <i32> [#uses=1]
%tmp1004 = lshr i32 %tmp98993, 3 ; <i32> [#uses=1]
%tmp100.lobit5 = and i32 %tmp1004, 1 ; <i32> [#uses=1]
ret i32 %tmp100.lobit5
UnifiedReturnBlock: ; preds = %entry
ret i32 0
}