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| author | Guozhi Wei <carrot@google.com> | 2019-12-04 16:01:20 -0800 |
|---|---|---|
| committer | Guozhi Wei <carrot@google.com> | 2019-12-06 09:53:53 -0800 |
| commit | 72942459d070cbfe6f3524e89c3ac37440be7890 (patch) | |
| tree | 6a45cb456c8fff75ba7c89eb4156254ef6d485d8 /llvm/test/CodeGen/X86/tail-dup-repeat.ll | |
| parent | 164e0fc5c7f782b174db5c87b37725ea0e174853 (diff) | |
| download | bcm5719-llvm-72942459d070cbfe6f3524e89c3ac37440be7890.tar.gz bcm5719-llvm-72942459d070cbfe6f3524e89c3ac37440be7890.zip | |
[MBP] Avoid tail duplication if it can't bring benefit
Current tail duplication integrated in bb layout is designed to increase the fallthrough from a BB's predecessor to its successor, but we have observed cases that duplication doesn't increase fallthrough, or it brings too much size overhead.
To overcome these two issues in function canTailDuplicateUnplacedPreds I add two checks:
make sure there is at least one duplication in current work set.
the number of duplication should not exceed the number of successors.
The modification in hasBetterLayoutPredecessor fixes a bug that potential predecessor must be at the bottom of a chain.
Differential Revision: https://reviews.llvm.org/D64376
Diffstat (limited to 'llvm/test/CodeGen/X86/tail-dup-repeat.ll')
| -rw-r--r-- | llvm/test/CodeGen/X86/tail-dup-repeat.ll | 11 |
1 files changed, 8 insertions, 3 deletions
diff --git a/llvm/test/CodeGen/X86/tail-dup-repeat.ll b/llvm/test/CodeGen/X86/tail-dup-repeat.ll index bfa1ee61145..9a06c9a723b 100644 --- a/llvm/test/CodeGen/X86/tail-dup-repeat.ll +++ b/llvm/test/CodeGen/X86/tail-dup-repeat.ll @@ -10,28 +10,33 @@ define void @repeated_tail_dup(i1 %a1, i1 %a2, i32* %a4, i32* %a5, i8* %a6, i32 %a7) #0 align 2 { ; CHECK-LABEL: repeated_tail_dup: ; CHECK: # %bb.0: # %entry -; CHECK-NEXT: testb $1, %dil -; CHECK-NEXT: je .LBB0_3 +; CHECK-NEXT: jmp .LBB0_1 ; CHECK-NEXT: .p2align 4, 0x90 ; CHECK-NEXT: .LBB0_2: # %land.lhs.true +; CHECK-NEXT: # in Loop: Header=BB0_1 Depth=1 ; CHECK-NEXT: movl $10, (%rdx) ; CHECK-NEXT: .LBB0_6: # %dup2 +; CHECK-NEXT: # in Loop: Header=BB0_1 Depth=1 ; CHECK-NEXT: movl $2, (%rcx) ; CHECK-NEXT: testl %r9d, %r9d ; CHECK-NEXT: jne .LBB0_8 ; CHECK-NEXT: .LBB0_1: # %for.cond +; CHECK-NEXT: # =>This Inner Loop Header: Depth=1 ; CHECK-NEXT: testb $1, %dil ; CHECK-NEXT: jne .LBB0_2 -; CHECK-NEXT: .LBB0_3: # %if.end56 +; CHECK-NEXT: # %bb.3: # %if.end56 +; CHECK-NEXT: # in Loop: Header=BB0_1 Depth=1 ; CHECK-NEXT: testb $1, %sil ; CHECK-NEXT: je .LBB0_5 ; CHECK-NEXT: # %bb.4: # %if.then64 +; CHECK-NEXT: # in Loop: Header=BB0_1 Depth=1 ; CHECK-NEXT: movb $1, (%r8) ; CHECK-NEXT: testl %r9d, %r9d ; CHECK-NEXT: je .LBB0_1 ; CHECK-NEXT: jmp .LBB0_8 ; CHECK-NEXT: .p2align 4, 0x90 ; CHECK-NEXT: .LBB0_5: # %if.end70 +; CHECK-NEXT: # in Loop: Header=BB0_1 Depth=1 ; CHECK-NEXT: movl $12, (%rdx) ; CHECK-NEXT: jmp .LBB0_6 ; CHECK-NEXT: .LBB0_8: # %for.end |
