llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT--> @llvm/pr-subscribers-llvm-transforms Author: Iris (el-ev) <details> <summary>Changes</summary> --- Full diff: https://github.com/llvm/llvm-project/pull/135785.diff 2 Files Affected: - (modified) llvm/lib/Transforms/Scalar/ConstraintElimination.cpp (+10) - (modified) llvm/test/Transforms/ConstraintElimination/usub-with-overflow.ll (+11-22) ``````````diff diff --git a/llvm/lib/Transforms/Scalar/ConstraintElimination.cpp b/llvm/lib/Transforms/Scalar/ConstraintElimination.cpp index 7ebd91dbb8ce4..412e59b3e7683 100644 --- a/llvm/lib/Transforms/Scalar/ConstraintElimination.cpp +++ b/llvm/lib/Transforms/Scalar/ConstraintElimination.cpp @@ -1123,6 +1123,7 @@ void State::addInfoFor(BasicBlock &BB) { // Enqueue overflow intrinsics for simplification. case Intrinsic::sadd_with_overflow: case Intrinsic::ssub_with_overflow: + case Intrinsic::usub_with_overflow: case Intrinsic::ucmp: case Intrinsic::scmp: WorkList.push_back( @@ -1785,6 +1786,15 @@ tryToSimplifyOverflowMath(IntrinsicInst *II, ConstraintInfo &Info, Changed = replaceSubOverflowUses(II, A, B, ToRemove); break; } + case Intrinsic::usub_with_overflow: { + // usub overflows iff A < B + // TODO: If the operation is guaranteed to overflow, we could + // also apply some simplifications. + if (DoesConditionHold(CmpInst::ICMP_UGE, A, B, Info)) { + Changed = replaceSubOverflowUses(II, A, B, ToRemove); + } + break; + } } return Changed; diff --git a/llvm/test/Transforms/ConstraintElimination/usub-with-overflow.ll b/llvm/test/Transforms/ConstraintElimination/usub-with-overflow.ll index 06bfd8269d97d..0a3c4eb00fd25 100644 --- a/llvm/test/Transforms/ConstraintElimination/usub-with-overflow.ll +++ b/llvm/test/Transforms/ConstraintElimination/usub-with-overflow.ll @@ -9,11 +9,9 @@ define i8 @usub_no_overflow_due_to_cmp_condition(i8 %a, i8 %b) { ; CHECK-NEXT: [[C_1:%.*]] = icmp uge i8 [[B:%.*]], [[A:%.*]] ; CHECK-NEXT: br i1 [[C_1]], label [[MATH:%.*]], label [[EXIT_FAIL:%.*]] ; CHECK: math: -; CHECK-NEXT: [[OP:%.*]] = tail call { i8, i1 } @llvm.usub.with.overflow.i8(i8 [[B]], i8 [[A]]) -; CHECK-NEXT: [[STATUS:%.*]] = extractvalue { i8, i1 } [[OP]], 1 -; CHECK-NEXT: br i1 [[STATUS]], label [[EXIT_FAIL]], label [[EXIT_OK:%.*]] +; CHECK-NEXT: [[RES:%.*]] = sub i8 [[B]], [[A]] +; CHECK-NEXT: br i1 false, label [[EXIT_FAIL]], label [[EXIT_OK:%.*]] ; CHECK: exit.ok: -; CHECK-NEXT: [[RES:%.*]] = extractvalue { i8, i1 } [[OP]], 0 ; CHECK-NEXT: ret i8 [[RES]] ; CHECK: exit.fail: ; CHECK-NEXT: ret i8 0 @@ -41,11 +39,9 @@ define i8 @usub_no_overflow_due_to_cmp_condition2(i8 %a, i8 %b) { ; CHECK-NEXT: [[C_1:%.*]] = icmp ule i8 [[B:%.*]], [[A:%.*]] ; CHECK-NEXT: br i1 [[C_1]], label [[EXIT_FAIL:%.*]], label [[MATH:%.*]] ; CHECK: math: -; CHECK-NEXT: [[OP:%.*]] = tail call { i8, i1 } @llvm.usub.with.overflow.i8(i8 [[B]], i8 [[A]]) -; CHECK-NEXT: [[STATUS:%.*]] = extractvalue { i8, i1 } [[OP]], 1 -; CHECK-NEXT: br i1 [[STATUS]], label [[EXIT_FAIL]], label [[EXIT_OK:%.*]] +; CHECK-NEXT: [[RES:%.*]] = sub i8 [[B]], [[A]] +; CHECK-NEXT: br i1 false, label [[EXIT_FAIL]], label [[EXIT_OK:%.*]] ; CHECK: exit.ok: -; CHECK-NEXT: [[RES:%.*]] = extractvalue { i8, i1 } [[OP]], 0 ; CHECK-NEXT: ret i8 [[RES]] ; CHECK: exit.fail: ; CHECK-NEXT: ret i8 0 @@ -75,12 +71,11 @@ define i8 @sub_no_overflow_due_to_cmp_condition_result_used(i8 %a, i8 %b) { ; CHECK-NEXT: [[C_1:%.*]] = icmp ule i8 [[B:%.*]], [[A:%.*]] ; CHECK-NEXT: br i1 [[C_1]], label [[EXIT_FAIL:%.*]], label [[MATH:%.*]] ; CHECK: math: +; CHECK-NEXT: [[RES:%.*]] = sub i8 [[B]], [[A]] ; CHECK-NEXT: [[OP:%.*]] = tail call { i8, i1 } @llvm.usub.with.overflow.i8(i8 [[B]], i8 [[A]]) ; CHECK-NEXT: call void @use_res({ i8, i1 } [[OP]]) -; CHECK-NEXT: [[STATUS:%.*]] = extractvalue { i8, i1 } [[OP]], 1 -; CHECK-NEXT: br i1 [[STATUS]], label [[EXIT_FAIL]], label [[EXIT_OK:%.*]] +; CHECK-NEXT: br i1 false, label [[EXIT_FAIL]], label [[EXIT_OK:%.*]] ; CHECK: exit.ok: -; CHECK-NEXT: [[RES:%.*]] = extractvalue { i8, i1 } [[OP]], 0 ; CHECK-NEXT: ret i8 [[RES]] ; CHECK: exit.fail: ; CHECK-NEXT: ret i8 0 @@ -111,11 +106,9 @@ define i8 @usub_no_overflow_due_to_or_conds(i8 %a, i8 %b) { ; CHECK-NEXT: [[OR:%.*]] = or i1 [[C_2]], [[C_1]] ; CHECK-NEXT: br i1 [[OR]], label [[EXIT_FAIL:%.*]], label [[MATH:%.*]] ; CHECK: math: -; CHECK-NEXT: [[OP:%.*]] = tail call { i8, i1 } @llvm.usub.with.overflow.i8(i8 [[B]], i8 [[A]]) -; CHECK-NEXT: [[STATUS:%.*]] = extractvalue { i8, i1 } [[OP]], 1 -; CHECK-NEXT: br i1 [[STATUS]], label [[EXIT_FAIL]], label [[EXIT_OK:%.*]] +; CHECK-NEXT: [[RES:%.*]] = sub i8 [[B]], [[A]] +; CHECK-NEXT: br i1 false, label [[EXIT_FAIL]], label [[EXIT_OK:%.*]] ; CHECK: exit.ok: -; CHECK-NEXT: [[RES:%.*]] = extractvalue { i8, i1 } [[OP]], 0 ; CHECK-NEXT: ret i8 [[RES]] ; CHECK: exit.fail: ; CHECK-NEXT: ret i8 0 @@ -147,9 +140,7 @@ define i8 @usub_no_overflow_due_to_or_conds_sub_result_not_used(i8 %a, i8 %b) { ; CHECK-NEXT: [[OR:%.*]] = or i1 [[C_2]], [[C_1]] ; CHECK-NEXT: br i1 [[OR]], label [[EXIT_FAIL:%.*]], label [[MATH:%.*]] ; CHECK: math: -; CHECK-NEXT: [[OP:%.*]] = tail call { i8, i1 } @llvm.usub.with.overflow.i8(i8 [[B]], i8 [[A]]) -; CHECK-NEXT: [[STATUS:%.*]] = extractvalue { i8, i1 } [[OP]], 1 -; CHECK-NEXT: br i1 [[STATUS]], label [[EXIT_FAIL]], label [[EXIT_OK:%.*]] +; CHECK-NEXT: br i1 false, label [[EXIT_FAIL]], label [[EXIT_OK:%.*]] ; CHECK: exit.ok: ; CHECK-NEXT: ret i8 20 ; CHECK: exit.fail: @@ -181,11 +172,9 @@ define i8 @usub_no_overflow_due_to_and_conds(i8 %a, i8 %b) { ; CHECK-NEXT: [[AND:%.*]] = and i1 [[C_2]], [[C_1]] ; CHECK-NEXT: br i1 [[AND]], label [[MATH:%.*]], label [[EXIT_FAIL:%.*]] ; CHECK: math: -; CHECK-NEXT: [[OP:%.*]] = tail call { i8, i1 } @llvm.usub.with.overflow.i8(i8 [[B]], i8 [[A]]) -; CHECK-NEXT: [[STATUS:%.*]] = extractvalue { i8, i1 } [[OP]], 1 -; CHECK-NEXT: br i1 [[STATUS]], label [[EXIT_FAIL]], label [[EXIT_OK:%.*]] +; CHECK-NEXT: [[RES:%.*]] = sub i8 [[B]], [[A]] +; CHECK-NEXT: br i1 false, label [[EXIT_FAIL]], label [[EXIT_OK:%.*]] ; CHECK: exit.ok: -; CHECK-NEXT: [[RES:%.*]] = extractvalue { i8, i1 } [[OP]], 0 ; CHECK-NEXT: ret i8 [[RES]] ; CHECK: exit.fail: ; CHECK-NEXT: ret i8 0 `````````` </details> https://github.com/llvm/llvm-project/pull/135785 _______________________________________________ llvm-branch-commits mailing list [email protected] https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-branch-commits
