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1970824078
If the stores are storing values from loads which partially alias the stores, we could end up placing the merged loads and stores on the same chain which has the potential to break. Each store may have a different chain dependency on only some of the original loads. Create a new TokenFactor to capture all of the required dependencies of the stores rather than assuming all stores can use the same chain. The testcase is a situation where this happens, although it does not have an observable change from this. The DAG nodes just happened to not be reordered before despite this missing chain dependency. This is based on an off-list report for an out of tree target which regressed due to r246307 and I haven't managed to find a case where the nodes do end up reordered with an in tree target. llvm-svn: 248468
54 lines
2.3 KiB
LLVM
54 lines
2.3 KiB
LLVM
; REQUIRES: asserts
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; RUN: llc -march=x86-64 -mtriple=x86_64-unknown-linux-gnu < %s | FileCheck -check-prefix=X86 %s
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; RUN: llc -march=x86-64 -mtriple=x86_64-unknown-linux-gnu -debug-only=isel < %s 2>&1 | FileCheck -check-prefix=DBGDAG %s
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; It's OK to merge the load / store of the first 2 components, but
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; they must not be placed on the same chain after merging.
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; X86-LABEL: {{^}}merge_store_partial_overlap_load:
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; X86-DAG: movw ([[BASEREG:%[a-z]+]]), [[LO2:%[a-z]+]]
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; X86-DAG: movb 2([[BASEREG]]), [[HI1:%[a-z]+]]
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; X86-NEXT: movw [[LO2]], 1([[BASEREG]])
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; X86-NEXT: movb [[HI1]], 3([[BASEREG]])
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; X86-NEXT: retq
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; DBGDAG-LABEL: Optimized lowered selection DAG: BB#0 'merge_store_partial_overlap_load:'
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; DBGDAG: [[ENTRYTOKEN:t[0-9]+]]: ch = EntryToken
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; DBGDAG-DAG: [[TWO:t[0-9]+]]: i64 = Constant<2>
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; DBGDAG-DAG: [[BASEPTR:t[0-9]+]]: i64,ch = CopyFromReg [[ENTRYTOKEN]],
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; DBGDAG-DAG: [[ADDPTR:t[0-9]+]]: i64 = add [[BASEPTR]], [[TWO]]
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; DBGDAG-DAG: [[LD2:t[0-9]+]]: i16,ch = load [[ENTRYTOKEN]], [[BASEPTR]], t{{[0-9]+}}<LD2[%tmp81](align=1)>
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; DBGDAG-DAG: [[LD1:t[0-9]+]]: i8,ch = load [[ENTRYTOKEN]], [[ADDPTR]], t{{[0-9]+}}<LD1[%tmp12]>
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; DBGDAG: [[LOADTOKEN:t[0-9]+]]: ch = TokenFactor [[LD2]]:1, [[LD1]]:1
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; DBGDAG-DAG: [[ST2:t[0-9]+]]: ch = store [[LOADTOKEN]], [[LD2]], t{{[0-9]+}}, t{{[0-9]+}}<ST2[%tmp10](align=1)>
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; DBGDAG-DAG: [[ST1:t[0-9]+]]: ch = store [[ST2]], [[LD1]], t{{[0-9]+}}, t{{[0-9]+}}<ST1[%tmp14]>
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; DBGDAG: X86ISD::RET_FLAG [[ST1]],
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; DBGDAG: Type-legalized selection DAG: BB#0 'merge_store_partial_overlap_load:'
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define void @merge_store_partial_overlap_load([4 x i8]* %tmp) {
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%tmp8 = getelementptr inbounds [4 x i8], [4 x i8]* %tmp, i32 0, i8 0
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%tmp10 = getelementptr inbounds [4 x i8], [4 x i8]* %tmp, i32 0, i8 1
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%tmp12 = getelementptr inbounds [4 x i8], [4 x i8]* %tmp, i32 0, i8 2
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%tmp14 = getelementptr [4 x i8], [4 x i8]* %tmp, i32 0, i8 3
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%tmp9 = load i8, i8* %tmp8, align 1 ; base + 0
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%tmp11 = load i8, i8* %tmp10, align 1 ; base + 1
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%tmp13 = load i8, i8* %tmp12, align 1 ; base + 2
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store i8 %tmp9, i8* %tmp10, align 1 ; base + 1
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store i8 %tmp11, i8* %tmp12, align 1 ; base + 2
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store i8 %tmp13, i8* %tmp14, align 1 ; base + 3
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; Should emit
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; load base + 0, base + 1
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; store base + 1, base + 2
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; load base + 2
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; store base + 3
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ret void
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}
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