Author: Yingwei Zheng Date: 2024-12-02T09:30:40+01:00 New Revision: 0e7e5d9bdf3c130069a1d622dc9a2b71357fc1ee
URL: https://github.com/llvm/llvm-project/commit/0e7e5d9bdf3c130069a1d622dc9a2b71357fc1ee DIFF: https://github.com/llvm/llvm-project/commit/0e7e5d9bdf3c130069a1d622dc9a2b71357fc1ee.diff LOG: [InstCombine] Drop noundef attributes in `foldCttzCtlz` (#116718) Closes https://github.com/llvm/llvm-project/issues/112068. (cherry picked from commit a59976bea8ad76f18119a11391dc8ba3e6ba07d5) Added: Modified: llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp llvm/test/Transforms/InstCombine/shift-cttz-ctlz.ll Removed: ################################################################################ diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp index 9d2990c98ce275..3223fccbcf49a9 100644 --- a/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp +++ b/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp @@ -506,8 +506,10 @@ static Instruction *foldCttzCtlz(IntrinsicInst &II, InstCombinerImpl &IC) { // If ctlz/cttz is only used as a shift amount, set is_zero_poison to true. if (II.hasOneUse() && match(Op1, m_Zero()) && - match(II.user_back(), m_Shift(m_Value(), m_Specific(&II)))) + match(II.user_back(), m_Shift(m_Value(), m_Specific(&II)))) { + II.dropUBImplyingAttrsAndMetadata(); return IC.replaceOperand(II, 1, IC.Builder.getTrue()); + } Constant *C; diff --git a/llvm/test/Transforms/InstCombine/shift-cttz-ctlz.ll b/llvm/test/Transforms/InstCombine/shift-cttz-ctlz.ll index 1c381d08390715..63caec95013254 100644 --- a/llvm/test/Transforms/InstCombine/shift-cttz-ctlz.ll +++ b/llvm/test/Transforms/InstCombine/shift-cttz-ctlz.ll @@ -15,6 +15,22 @@ entry: ret i32 %res } +; Make sure that noundef is dropped. + +define i32 @shl_cttz_false_noundef(i32 %x, i32 %y) { +; CHECK-LABEL: define i32 @shl_cttz_false_noundef( +; CHECK-SAME: i32 [[X:%.*]], i32 [[Y:%.*]]) { +; CHECK-NEXT: entry: +; CHECK-NEXT: [[CTTZ:%.*]] = call range(i32 0, 33) i32 @llvm.cttz.i32(i32 [[Y]], i1 true) +; CHECK-NEXT: [[RES:%.*]] = shl i32 [[X]], [[CTTZ]] +; CHECK-NEXT: ret i32 [[RES]] +; +entry: + %cttz = call noundef i32 @llvm.cttz.i32(i32 %y, i1 false) + %res = shl i32 %x, %cttz + ret i32 %res +} + define i32 @shl_ctlz_false(i32 %x, i32 %y) { ; CHECK-LABEL: define i32 @shl_ctlz_false( ; CHECK-SAME: i32 [[X:%.*]], i32 [[Y:%.*]]) { _______________________________________________ llvm-branch-commits mailing list llvm-branch-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-branch-commits
