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86eb682529
Summary: This is last in of a series of patches to evolve ADCE.cpp to support removing of unnecessary control flow. This patch adds the code to update the control and data flow graphs to remove the dead control flow. Also update unit tests to test the capability to remove dead, may-be-infinite loop which is enabled by the switch -adce-remove-loops. Previous patches: D23824 [ADCE] Add handling of PHI nodes when removing control flow D23559 [ADCE] Add control dependence computation D23225 [ADCE] Modify data structures to support removing control flow D23065 [ADCE] Refactor anticipating new functionality (NFC) D23102 [ADCE] Refactoring for new functionality (NFC) Reviewers: dberlin, majnemer, nadav, mehdi_amini Subscribers: llvm-commits, david2050, freik, twoh Differential Revision: https://reviews.llvm.org/D24918 llvm-svn: 289548
57 lines
2.8 KiB
LLVM
57 lines
2.8 KiB
LLVM
; This testcase is distilled from the GNU rx package. The loop should be
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; removed but causes a problem when ADCE does. The source function is:
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; int rx_bitset_empty (int size, rx_Bitset set) {
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; int x;
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; RX_subset s;
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; s = set[0];
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; set[0] = 1;
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; for (x = rx_bitset_numb_subsets(size) - 1; !set[x]; --x)
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; ;
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; set[0] = s;
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; return !s;
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;}
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;
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; RUN: opt < %s -adce
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; RUN: opt < %s -adce -adce-remove-loops -S | FileCheck %s
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define i32 @rx_bitset_empty(i32 %size, i32* %set) {
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bb1:
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%reg110 = load i32, i32* %set ; <i32> [#uses=2]
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store i32 1, i32* %set
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%cast112 = sext i32 %size to i64 ; <i64> [#uses=1]
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%reg113 = add i64 %cast112, 31 ; <i64> [#uses=1]
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%reg114 = lshr i64 %reg113, 5 ; <i64> [#uses=2]
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%cast109 = trunc i64 %reg114 to i32 ; <i32> [#uses=1]
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%reg129 = add i32 %cast109, -1 ; <i32> [#uses=1]
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%reg114-idxcast = trunc i64 %reg114 to i32 ; <i32> [#uses=1]
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%reg114-idxcast-offset = add i32 %reg114-idxcast, 1073741823 ; <i32> [#uses=1]
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%reg114-idxcast-offset.upgrd.1 = zext i32 %reg114-idxcast-offset to i64 ; <i64> [#uses=1]
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%reg124 = getelementptr i32, i32* %set, i64 %reg114-idxcast-offset.upgrd.1 ; <i32*> [#uses=1]
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%reg125 = load i32, i32* %reg124 ; <i32> [#uses=1]
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%cond232 = icmp ne i32 %reg125, 0 ; <i1> [#uses=1]
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; CHECK: br label %bb3
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br i1 %cond232, label %bb3, label %bb2
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bb2: ; preds = %bb2, %bb1
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%cann-indvar = phi i32 [ 0, %bb1 ], [ %add1-indvar, %bb2 ] ; <i32> [#uses=2]
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%reg130-scale = mul i32 %cann-indvar, -1 ; <i32> [#uses=1]
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%reg130 = add i32 %reg130-scale, %reg129 ; <i32> [#uses=1]
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%add1-indvar = add i32 %cann-indvar, 1 ; <i32> [#uses=1]
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%reg130-idxcast = bitcast i32 %reg130 to i32 ; <i32> [#uses=1]
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%reg130-idxcast-offset = add i32 %reg130-idxcast, 1073741823 ; <i32> [#uses=1]
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%reg130-idxcast-offset.upgrd.2 = zext i32 %reg130-idxcast-offset to i64 ; <i64> [#uses=1]
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%reg118 = getelementptr i32, i32* %set, i64 %reg130-idxcast-offset.upgrd.2 ; <i32*> [#uses=1]
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%reg119 = load i32, i32* %reg118 ; <i32> [#uses=1]
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%cond233 = icmp eq i32 %reg119, 0 ; <i1> [#uses=1]
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br i1 %cond233, label %bb2, label %bb3
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bb3: ; preds = %bb2, %bb1
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store i32 %reg110, i32* %set
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%cast126 = zext i32 %reg110 to i64 ; <i64> [#uses=1]
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%reg127 = add i64 %cast126, -1 ; <i64> [#uses=1]
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%reg128 = lshr i64 %reg127, 63 ; <i64> [#uses=1]
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%cast120 = trunc i64 %reg128 to i32 ; <i32> [#uses=1]
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ret i32 %cast120
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}
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