diff options
| -rw-r--r-- | lib/Analysis/MemoryDependenceAnalysis.cpp | 11 | ||||
| -rw-r--r-- | test/Transforms/DeadStoreElimination/inst-limits.ll | 260 |
2 files changed, 266 insertions, 5 deletions
diff --git a/lib/Analysis/MemoryDependenceAnalysis.cpp b/lib/Analysis/MemoryDependenceAnalysis.cpp index fe1c874..84ff2ee 100644 --- a/lib/Analysis/MemoryDependenceAnalysis.cpp +++ b/lib/Analysis/MemoryDependenceAnalysis.cpp @@ -371,18 +371,19 @@ getPointerDependencyFrom(const AliasAnalysis::Location &MemLoc, bool isLoad, // Walk backwards through the basic block, looking for dependencies. while (ScanIt != BB->begin()) { + Instruction *Inst = --ScanIt; + + if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(Inst)) + // Debug intrinsics don't (and can't) cause dependencies. + if (isa<DbgInfoIntrinsic>(II)) continue; + // Limit the amount of scanning we do so we don't end up with quadratic // running time on extreme testcases. --Limit; if (!Limit) return MemDepResult::getUnknown(); - Instruction *Inst = --ScanIt; - if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(Inst)) { - // Debug intrinsics don't (and can't) cause dependences. - if (isa<DbgInfoIntrinsic>(II)) continue; - // If we reach a lifetime begin or end marker, then the query ends here // because the value is undefined. if (II->getIntrinsicID() == Intrinsic::lifetime_start) { diff --git a/test/Transforms/DeadStoreElimination/inst-limits.ll b/test/Transforms/DeadStoreElimination/inst-limits.ll new file mode 100644 index 0000000..1cdf0e1 --- /dev/null +++ b/test/Transforms/DeadStoreElimination/inst-limits.ll @@ -0,0 +1,260 @@ +; RUN: opt -S -dse < %s | FileCheck %s + +; If there are two stores to the same location, DSE should be able to remove +; the first store if the two stores are separated by no more than 98 +; instructions. The existence of debug intrinsics between the stores should +; not affect this instruction limit. + +@x = global i32 0, align 4 + +; Function Attrs: nounwind +define i32 @test_within_limit() { +entry: + ; The first store; later there is a second store to the same location, + ; so this store should be optimized away by DSE. + ; CHECK-NOT: store i32 1, i32* @x, align 4 + store i32 1, i32* @x, align 4 + + ; Insert 98 dummy instructions between the two stores + %0 = bitcast i32 0 to i32 + %1 = bitcast i32 0 to i32 + %2 = bitcast i32 0 to i32 + %3 = bitcast i32 0 to i32 + %4 = bitcast i32 0 to i32 + %5 = bitcast i32 0 to i32 + %6 = bitcast i32 0 to i32 + %7 = bitcast i32 0 to i32 + %8 = bitcast i32 0 to i32 + %9 = bitcast i32 0 to i32 + %10 = bitcast i32 0 to i32 + %11 = bitcast i32 0 to i32 + %12 = bitcast i32 0 to i32 + %13 = bitcast i32 0 to i32 + %14 = bitcast i32 0 to i32 + %15 = bitcast i32 0 to i32 + %16 = bitcast i32 0 to i32 + %17 = bitcast i32 0 to i32 + %18 = bitcast i32 0 to i32 + %19 = bitcast i32 0 to i32 + %20 = bitcast i32 0 to i32 + %21 = bitcast i32 0 to i32 + %22 = bitcast i32 0 to i32 + %23 = bitcast i32 0 to i32 + %24 = bitcast i32 0 to i32 + %25 = bitcast i32 0 to i32 + %26 = bitcast i32 0 to i32 + %27 = bitcast i32 0 to i32 + %28 = bitcast i32 0 to i32 + %29 = bitcast i32 0 to i32 + %30 = bitcast i32 0 to i32 + %31 = bitcast i32 0 to i32 + %32 = bitcast i32 0 to i32 + %33 = bitcast i32 0 to i32 + %34 = bitcast i32 0 to i32 + %35 = bitcast i32 0 to i32 + %36 = bitcast i32 0 to i32 + %37 = bitcast i32 0 to i32 + %38 = bitcast i32 0 to i32 + %39 = bitcast i32 0 to i32 + %40 = bitcast i32 0 to i32 + %41 = bitcast i32 0 to i32 + %42 = bitcast i32 0 to i32 + %43 = bitcast i32 0 to i32 + %44 = bitcast i32 0 to i32 + %45 = bitcast i32 0 to i32 + %46 = bitcast i32 0 to i32 + %47 = bitcast i32 0 to i32 + %48 = bitcast i32 0 to i32 + %49 = bitcast i32 0 to i32 + %50 = bitcast i32 0 to i32 + %51 = bitcast i32 0 to i32 + %52 = bitcast i32 0 to i32 + %53 = bitcast i32 0 to i32 + %54 = bitcast i32 0 to i32 + %55 = bitcast i32 0 to i32 + %56 = bitcast i32 0 to i32 + %57 = bitcast i32 0 to i32 + %58 = bitcast i32 0 to i32 + %59 = bitcast i32 0 to i32 + %60 = bitcast i32 0 to i32 + %61 = bitcast i32 0 to i32 + %62 = bitcast i32 0 to i32 + %63 = bitcast i32 0 to i32 + %64 = bitcast i32 0 to i32 + %65 = bitcast i32 0 to i32 + %66 = bitcast i32 0 to i32 + %67 = bitcast i32 0 to i32 + %68 = bitcast i32 0 to i32 + %69 = bitcast i32 0 to i32 + %70 = bitcast i32 0 to i32 + %71 = bitcast i32 0 to i32 + %72 = bitcast i32 0 to i32 + %73 = bitcast i32 0 to i32 + %74 = bitcast i32 0 to i32 + %75 = bitcast i32 0 to i32 + %76 = bitcast i32 0 to i32 + %77 = bitcast i32 0 to i32 + %78 = bitcast i32 0 to i32 + %79 = bitcast i32 0 to i32 + %80 = bitcast i32 0 to i32 + %81 = bitcast i32 0 to i32 + %82 = bitcast i32 0 to i32 + %83 = bitcast i32 0 to i32 + %84 = bitcast i32 0 to i32 + %85 = bitcast i32 0 to i32 + %86 = bitcast i32 0 to i32 + %87 = bitcast i32 0 to i32 + %88 = bitcast i32 0 to i32 + %89 = bitcast i32 0 to i32 + %90 = bitcast i32 0 to i32 + %91 = bitcast i32 0 to i32 + %92 = bitcast i32 0 to i32 + %93 = bitcast i32 0 to i32 + %94 = bitcast i32 0 to i32 + %95 = bitcast i32 0 to i32 + %96 = bitcast i32 0 to i32 + %97 = bitcast i32 0 to i32 + + ; Insert a meaningless dbg.value intrinsic; it should have no + ; effect on the working of DSE in any way. + call void @llvm.dbg.value(metadata !12, i64 0, metadata !10) + + ; CHECK: store i32 -1, i32* @x, align 4 + store i32 -1, i32* @x, align 4 + ret i32 0 +} + +; Function Attrs: nounwind +define i32 @test_outside_limit() { +entry: + ; The first store; later there is a second store to the same location + ; CHECK: store i32 1, i32* @x, align 4 + store i32 1, i32* @x, align 4 + + ; Insert 99 dummy instructions between the two stores; this is + ; one too many instruction for the DSE to take place. + %0 = bitcast i32 0 to i32 + %1 = bitcast i32 0 to i32 + %2 = bitcast i32 0 to i32 + %3 = bitcast i32 0 to i32 + %4 = bitcast i32 0 to i32 + %5 = bitcast i32 0 to i32 + %6 = bitcast i32 0 to i32 + %7 = bitcast i32 0 to i32 + %8 = bitcast i32 0 to i32 + %9 = bitcast i32 0 to i32 + %10 = bitcast i32 0 to i32 + %11 = bitcast i32 0 to i32 + %12 = bitcast i32 0 to i32 + %13 = bitcast i32 0 to i32 + %14 = bitcast i32 0 to i32 + %15 = bitcast i32 0 to i32 + %16 = bitcast i32 0 to i32 + %17 = bitcast i32 0 to i32 + %18 = bitcast i32 0 to i32 + %19 = bitcast i32 0 to i32 + %20 = bitcast i32 0 to i32 + %21 = bitcast i32 0 to i32 + %22 = bitcast i32 0 to i32 + %23 = bitcast i32 0 to i32 + %24 = bitcast i32 0 to i32 + %25 = bitcast i32 0 to i32 + %26 = bitcast i32 0 to i32 + %27 = bitcast i32 0 to i32 + %28 = bitcast i32 0 to i32 + %29 = bitcast i32 0 to i32 + %30 = bitcast i32 0 to i32 + %31 = bitcast i32 0 to i32 + %32 = bitcast i32 0 to i32 + %33 = bitcast i32 0 to i32 + %34 = bitcast i32 0 to i32 + %35 = bitcast i32 0 to i32 + %36 = bitcast i32 0 to i32 + %37 = bitcast i32 0 to i32 + %38 = bitcast i32 0 to i32 + %39 = bitcast i32 0 to i32 + %40 = bitcast i32 0 to i32 + %41 = bitcast i32 0 to i32 + %42 = bitcast i32 0 to i32 + %43 = bitcast i32 0 to i32 + %44 = bitcast i32 0 to i32 + %45 = bitcast i32 0 to i32 + %46 = bitcast i32 0 to i32 + %47 = bitcast i32 0 to i32 + %48 = bitcast i32 0 to i32 + %49 = bitcast i32 0 to i32 + %50 = bitcast i32 0 to i32 + %51 = bitcast i32 0 to i32 + %52 = bitcast i32 0 to i32 + %53 = bitcast i32 0 to i32 + %54 = bitcast i32 0 to i32 + %55 = bitcast i32 0 to i32 + %56 = bitcast i32 0 to i32 + %57 = bitcast i32 0 to i32 + %58 = bitcast i32 0 to i32 + %59 = bitcast i32 0 to i32 + %60 = bitcast i32 0 to i32 + %61 = bitcast i32 0 to i32 + %62 = bitcast i32 0 to i32 + %63 = bitcast i32 0 to i32 + %64 = bitcast i32 0 to i32 + %65 = bitcast i32 0 to i32 + %66 = bitcast i32 0 to i32 + %67 = bitcast i32 0 to i32 + %68 = bitcast i32 0 to i32 + %69 = bitcast i32 0 to i32 + %70 = bitcast i32 0 to i32 + %71 = bitcast i32 0 to i32 + %72 = bitcast i32 0 to i32 + %73 = bitcast i32 0 to i32 + %74 = bitcast i32 0 to i32 + %75 = bitcast i32 0 to i32 + %76 = bitcast i32 0 to i32 + %77 = bitcast i32 0 to i32 + %78 = bitcast i32 0 to i32 + %79 = bitcast i32 0 to i32 + %80 = bitcast i32 0 to i32 + %81 = bitcast i32 0 to i32 + %82 = bitcast i32 0 to i32 + %83 = bitcast i32 0 to i32 + %84 = bitcast i32 0 to i32 + %85 = bitcast i32 0 to i32 + %86 = bitcast i32 0 to i32 + %87 = bitcast i32 0 to i32 + %88 = bitcast i32 0 to i32 + %89 = bitcast i32 0 to i32 + %90 = bitcast i32 0 to i32 + %91 = bitcast i32 0 to i32 + %92 = bitcast i32 0 to i32 + %93 = bitcast i32 0 to i32 + %94 = bitcast i32 0 to i32 + %95 = bitcast i32 0 to i32 + %96 = bitcast i32 0 to i32 + %97 = bitcast i32 0 to i32 + %98 = bitcast i32 0 to i32 + + ; CHECK: store i32 -1, i32* @x, align 4 + store i32 -1, i32* @x, align 4 + ret i32 0 +} + +; Function Attrs: nounwind readnone +declare void @llvm.dbg.value(metadata, i64, metadata) + +!llvm.dbg.cu = !{!0} +!llvm.module.flags = !{!11} + +!0 = metadata !{i32 786449, metadata !1, i32 4, metadata !"clang version 3.4", i1 true, metadata !"", i32 0, metadata !2, metadata !2, metadata !3, metadata !9, metadata !2, metadata !""} ; [ DW_TAG_compile_unit ] [/home/tmp/test.c] [DW_LANG_C99] +!1 = metadata !{metadata !"test.c", metadata !"/home/tmp"} +!2 = metadata !{i32 0} +!3 = metadata !{metadata !4} +!4 = metadata !{i32 786478, metadata !1, metadata !5, metadata !"test_within_limit", metadata !"test_within_limit", metadata !"", i32 3, metadata !6, i1 false, i1 true, i32 0, i32 0, null, i32 256, i1 false, i32 ()* @test_within_limit, null, null, metadata !2, i32 4} ; [ DW_TAG_subprogram ] [line 3] [def] [scope 4] [test] +!5 = metadata !{i32 786473, metadata !1} ; [ DW_TAG_file_type ] [/home/tmp/test.c] +!6 = metadata !{i32 786453, i32 0, null, metadata !"", i32 0, i64 0, i64 0, i64 0, i32 0, null, metadata !7, i32 0, null, null, null} ; [ DW_TAG_subroutine_type ] [line 0, size 0, align 0, offset 0] [from ] +!7 = metadata !{metadata !8} +!8 = metadata !{i32 786468, null, null, metadata !"int", i32 0, i64 32, i64 32, i64 0, i32 0, i32 5} ; [ DW_TAG_base_type ] [int] [line 0, size 32, align 32, offset 0, enc DW_ATE_signed] +!9 = metadata !{metadata !10} +!10 = metadata !{i32 786484, i32 0, null, metadata !"x", metadata !"x", metadata !"", metadata !5, i32 1, metadata !8, i32 0, i32 1, i32* @x, null} ; [ DW_TAG_variable ] [x] [line 1] [def] +!11 = metadata !{i32 2, metadata !"Dwarf Version", i32 4} +!12 = metadata !{i32* undef} + |