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opportunities that only present themselves after late optimizations
such as tail duplication .e.g.
## BB#1:
movl %eax, %ecx
movl %ecx, %eax
ret
The register allocator also leaves some of them around (due to false
dep between copies from phi-elimination, etc.)
This required some changes in codegen passes. Post-ra scheduler and the
pseudo-instruction expansion passes have been moved after branch folding
and tail merging. They were before branch folding before because it did
not always update block livein's. That's fixed now. The pass change makes
independently since we want to properly schedule instructions after
branch folding / tail duplication.
rdar://10428165
rdar://10640363
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@147716 91177308-0d34-0410-b5e6-96231b3b80d8
80 lines
3.2 KiB
LLVM
80 lines
3.2 KiB
LLVM
; RUN: llc < %s -mtriple=armv7-apple-darwin | FileCheck %s
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; PHI elimination shouldn't break backedge.
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; rdar://8263994
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%struct.list_data_s = type { i16, i16 }
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%struct.list_head = type { %struct.list_head*, %struct.list_data_s* }
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define arm_apcscc %struct.list_head* @t1(%struct.list_head* %list) nounwind {
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entry:
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; CHECK: t1:
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%0 = icmp eq %struct.list_head* %list, null
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br i1 %0, label %bb2, label %bb
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bb:
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; CHECK: LBB0_1:
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; CHECK: bne LBB0_1
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; CHECK-NOT: b LBB0_1
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; CHECK: bx lr
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%list_addr.05 = phi %struct.list_head* [ %2, %bb ], [ %list, %entry ]
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%next.04 = phi %struct.list_head* [ %list_addr.05, %bb ], [ null, %entry ]
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%1 = getelementptr inbounds %struct.list_head* %list_addr.05, i32 0, i32 0
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%2 = load %struct.list_head** %1, align 4
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store %struct.list_head* %next.04, %struct.list_head** %1, align 4
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%3 = icmp eq %struct.list_head* %2, null
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br i1 %3, label %bb2, label %bb
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bb2:
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%next.0.lcssa = phi %struct.list_head* [ null, %entry ], [ %list_addr.05, %bb ]
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ret %struct.list_head* %next.0.lcssa
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}
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; Optimize loop entry, eliminate intra loop branches
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; rdar://8117827
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define i32 @t2(i32 %passes, i32* nocapture %src, i32 %size) nounwind readonly {
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entry:
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; CHECK: t2:
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; CHECK: beq LBB1_[[RET:.]]
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%0 = icmp eq i32 %passes, 0 ; <i1> [#uses=1]
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br i1 %0, label %bb5, label %bb.nph15
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; CHECK: LBB1_[[PREHDR:.]]: @ %bb2.preheader
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bb1: ; preds = %bb2.preheader, %bb1
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; CHECK: LBB1_[[BB1:.]]: @ %bb1
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; CHECK: bne LBB1_[[BB1]]
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%indvar = phi i32 [ %indvar.next, %bb1 ], [ 0, %bb2.preheader ] ; <i32> [#uses=2]
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%sum.08 = phi i32 [ %2, %bb1 ], [ %sum.110, %bb2.preheader ] ; <i32> [#uses=1]
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%tmp17 = sub i32 %i.07, %indvar ; <i32> [#uses=1]
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%scevgep = getelementptr i32* %src, i32 %tmp17 ; <i32*> [#uses=1]
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%1 = load i32* %scevgep, align 4 ; <i32> [#uses=1]
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%2 = add nsw i32 %1, %sum.08 ; <i32> [#uses=2]
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%indvar.next = add i32 %indvar, 1 ; <i32> [#uses=2]
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%exitcond = icmp eq i32 %indvar.next, %size ; <i1> [#uses=1]
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br i1 %exitcond, label %bb3, label %bb1
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bb3: ; preds = %bb1, %bb2.preheader
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; CHECK: LBB1_[[BB3:.]]: @ %bb3
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; CHECK: bne LBB1_[[PREHDR]]
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; CHECK-NOT: b LBB1_
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%sum.0.lcssa = phi i32 [ %sum.110, %bb2.preheader ], [ %2, %bb1 ] ; <i32> [#uses=2]
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%3 = add i32 %pass.011, 1 ; <i32> [#uses=2]
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%exitcond18 = icmp eq i32 %3, %passes ; <i1> [#uses=1]
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br i1 %exitcond18, label %bb5, label %bb2.preheader
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bb.nph15: ; preds = %entry
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%i.07 = add i32 %size, -1 ; <i32> [#uses=2]
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%4 = icmp sgt i32 %i.07, -1 ; <i1> [#uses=1]
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br label %bb2.preheader
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bb2.preheader: ; preds = %bb3, %bb.nph15
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%pass.011 = phi i32 [ 0, %bb.nph15 ], [ %3, %bb3 ] ; <i32> [#uses=1]
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%sum.110 = phi i32 [ 0, %bb.nph15 ], [ %sum.0.lcssa, %bb3 ] ; <i32> [#uses=2]
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br i1 %4, label %bb1, label %bb3
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; CHECK: LBB1_[[RET]]: @ %bb5
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; CHECK: pop
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bb5: ; preds = %bb3, %entry
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%sum.1.lcssa = phi i32 [ 0, %entry ], [ %sum.0.lcssa, %bb3 ] ; <i32> [#uses=1]
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ret i32 %sum.1.lcssa
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}
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