Author: Roman Lebedev Date: 2020-12-30T23:58:41+03:00 New Revision: 51879a525649c8151f7e841b66a5cea0e1c8e74e
URL: https://github.com/llvm/llvm-project/commit/51879a525649c8151f7e841b66a5cea0e1c8e74e DIFF: https://github.com/llvm/llvm-project/commit/51879a525649c8151f7e841b66a5cea0e1c8e74e.diff LOG: [LoopIdiom] 'left-shift until bittest': don't forget to check that PHI node is in loop header Fixes an issue reported by Peter Collingbourne in https://reviews.llvm.org/D91726#2475301 Added: Modified: llvm/lib/Transforms/Scalar/LoopIdiomRecognize.cpp llvm/test/Transforms/LoopIdiom/X86/left-shift-until-bittest.ll Removed: ################################################################################ diff --git a/llvm/lib/Transforms/Scalar/LoopIdiomRecognize.cpp b/llvm/lib/Transforms/Scalar/LoopIdiomRecognize.cpp index 3612f8cc1a71..8064c02e2b39 100644 --- a/llvm/lib/Transforms/Scalar/LoopIdiomRecognize.cpp +++ b/llvm/lib/Transforms/Scalar/LoopIdiomRecognize.cpp @@ -2024,8 +2024,8 @@ static bool detectShiftUntilBitTestIdiom(Loop *CurLoop, Value *&BaseX, // Step 3: Check if the recurrence is in desirable form. auto *CurrXPN = dyn_cast<PHINode>(CurrX); - if (!CurrXPN) { - LLVM_DEBUG(dbgs() << DEBUG_TYPE " Not a PHI node.\n"); + if (!CurrXPN || CurrXPN->getParent() != LoopHeaderBB) { + LLVM_DEBUG(dbgs() << DEBUG_TYPE " Not an expected PHI node.\n"); return false; } diff --git a/llvm/test/Transforms/LoopIdiom/X86/left-shift-until-bittest.ll b/llvm/test/Transforms/LoopIdiom/X86/left-shift-until-bittest.ll index 17ff7fc7663b..82dc8451382f 100644 --- a/llvm/test/Transforms/LoopIdiom/X86/left-shift-until-bittest.ll +++ b/llvm/test/Transforms/LoopIdiom/X86/left-shift-until-bittest.ll @@ -1812,3 +1812,84 @@ end: call void @use1(i1 %x.curr.isbitunset) ret i32 %x.curr } + +; %x.curr is not a PHI node +define i32 @n33(i32 %x, i32 %bit, i32 %x.curr) { +; ALL-LABEL: @n33( +; ALL-NEXT: entry: +; ALL-NEXT: [[BITMASK:%.*]] = shl i32 1, [[BIT:%.*]], [[DBG507:!dbg !.*]] +; ALL-NEXT: call void @llvm.dbg.value(metadata i32 [[BITMASK]], [[META503:metadata !.*]], metadata !DIExpression()), [[DBG507]] +; ALL-NEXT: br label [[LOOP:%.*]], [[DBG508:!dbg !.*]] +; ALL: loop: +; ALL-NEXT: [[X_CURR_BITMASKED:%.*]] = and i32 [[X_CURR:%.*]], [[BITMASK]], [[DBG509:!dbg !.*]] +; ALL-NEXT: call void @llvm.dbg.value(metadata i32 [[X_CURR_BITMASKED]], [[META504:metadata !.*]], metadata !DIExpression()), [[DBG509]] +; ALL-NEXT: [[X_CURR_ISBITUNSET:%.*]] = icmp eq i32 [[X_CURR_BITMASKED]], 0, [[DBG510:!dbg !.*]] +; ALL-NEXT: call void @llvm.dbg.value(metadata i1 [[X_CURR_ISBITUNSET]], [[META505:metadata !.*]], metadata !DIExpression()), [[DBG510]] +; ALL-NEXT: [[X_NEXT:%.*]] = shl i32 [[X_CURR]], 1, [[DBG511:!dbg !.*]] +; ALL-NEXT: call void @llvm.dbg.value(metadata i32 [[X_NEXT]], [[META506:metadata !.*]], metadata !DIExpression()), [[DBG511]] +; ALL-NEXT: br i1 [[X_CURR_ISBITUNSET]], label [[LOOP]], label [[END:%.*]], [[DBG512:!dbg !.*]] +; ALL: end: +; ALL-NEXT: ret i32 [[X_CURR]], [[DBG513:!dbg !.*]] +; +entry: + %bitmask = shl i32 1, %bit + br label %loop + +loop: + %x.curr.bitmasked = and i32 %x.curr, %bitmask + %x.curr.isbitunset = icmp eq i32 %x.curr.bitmasked, 0 + %x.next = shl i32 %x.curr, 1 + br i1 %x.curr.isbitunset, label %loop, label %end + +end: + ret i32 %x.curr +} + +; %x.curr is a PHI node in a wrong block +define i32 @n34(i32 %bit, i1 %c, i32 %x0, i32 %x1) { +; ALL-LABEL: @n34( +; ALL-NEXT: entry: +; ALL-NEXT: [[BITMASK:%.*]] = shl i32 1, [[BIT:%.*]], [[DBG521:!dbg !.*]] +; ALL-NEXT: call void @llvm.dbg.value(metadata i32 [[BITMASK]], [[META516:metadata !.*]], metadata !DIExpression()), [[DBG521]] +; ALL-NEXT: br i1 [[C:%.*]], label [[BB0:%.*]], label [[BB1:%.*]], [[DBG522:!dbg !.*]] +; ALL: bb0: +; ALL-NEXT: br label [[MERGE:%.*]], [[DBG523:!dbg !.*]] +; ALL: bb1: +; ALL-NEXT: br label [[MERGE]], [[DBG524:!dbg !.*]] +; ALL: merge: +; ALL-NEXT: [[X_CURR:%.*]] = phi i32 [ [[X0:%.*]], [[BB0]] ], [ [[X1:%.*]], [[BB1]] ], [[DBG525:!dbg !.*]] +; ALL-NEXT: call void @llvm.dbg.value(metadata i32 [[X_CURR]], [[META517:metadata !.*]], metadata !DIExpression()), [[DBG525]] +; ALL-NEXT: br label [[LOOP:%.*]], [[DBG526:!dbg !.*]] +; ALL: loop: +; ALL-NEXT: [[X_CURR_BITMASKED:%.*]] = and i32 [[X_CURR]], [[BITMASK]], [[DBG527:!dbg !.*]] +; ALL-NEXT: call void @llvm.dbg.value(metadata i32 [[X_CURR_BITMASKED]], [[META518:metadata !.*]], metadata !DIExpression()), [[DBG527]] +; ALL-NEXT: [[X_CURR_ISBITUNSET:%.*]] = icmp eq i32 [[X_CURR_BITMASKED]], 0, [[DBG528:!dbg !.*]] +; ALL-NEXT: call void @llvm.dbg.value(metadata i1 [[X_CURR_ISBITUNSET]], [[META519:metadata !.*]], metadata !DIExpression()), [[DBG528]] +; ALL-NEXT: [[X_NEXT:%.*]] = shl i32 [[X_CURR]], 1, [[DBG529:!dbg !.*]] +; ALL-NEXT: call void @llvm.dbg.value(metadata i32 [[X_NEXT]], [[META520:metadata !.*]], metadata !DIExpression()), [[DBG529]] +; ALL-NEXT: br i1 [[X_CURR_ISBITUNSET]], label [[LOOP]], label [[END:%.*]], [[DBG530:!dbg !.*]] +; ALL: end: +; ALL-NEXT: ret i32 [[X_CURR]], [[DBG531:!dbg !.*]] +; +entry: + %bitmask = shl i32 1, %bit + br i1 %c, label %bb0, label %bb1 + +bb0: + br label %merge +bb1: + br label %merge + +merge: + %x.curr = phi i32 [ %x0, %bb0 ], [ %x1, %bb1 ] + br label %loop + +loop: + %x.curr.bitmasked = and i32 %x.curr, %bitmask + %x.curr.isbitunset = icmp eq i32 %x.curr.bitmasked, 0 + %x.next = shl i32 %x.curr, 1 + br i1 %x.curr.isbitunset, label %loop, label %end + +end: + ret i32 %x.curr +} _______________________________________________ llvm-branch-commits mailing list llvm-branch-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-branch-commits
