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[IR] IRBuilderBase::CreateAnd(): short-circuit x & 0 --> 0
https://alive2.llvm.org/ce/z/YzPhSb Refs. https://reviews.llvm.org/D109368#3089809
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‎clang/test/CodeGen/catch-nullptr-and-nonzero-offset.c

Lines changed: 3 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -172,13 +172,13 @@ char *nullptr_var(unsigned long offset) {
172172
// CHECK-SANITIZE-NEXT: %[[COMPUTED_OFFSET:.*]] = extractvalue { i64, i1 } %[[COMPUTED_OFFSET_AGGREGATE]], 0, !nosanitize
173173
// CHECK-SANITIZE-NEXT: %[[COMPUTED_GEP:.*]] = add i64 0, %[[COMPUTED_OFFSET]], !nosanitize
174174
// CHECK-SANITIZE-NEXT: %[[COMPUTED_GEP_IS_NOT_NULL:.*]] = icmp ne i64 %[[COMPUTED_GEP]], 0, !nosanitize
175-
// CHECK-SANITIZE-C-NEXT: %[[BOTH_POINTERS_ARE_NULL_OR_BOTH_ARE_NONNULL:.*]] = and i1 %[[COMPUTED_GEP_IS_NOT_NULL]], false, !nosanitize
176175
// CHECK-SANITIZE-CPP-NEXT: %[[BOTH_POINTERS_ARE_NULL_OR_BOTH_ARE_NONNULL:.*]] = icmp eq i1 false, %[[COMPUTED_GEP_IS_NOT_NULL]], !nosanitize
177176
// CHECK-SANITIZE-NEXT: %[[COMPUTED_OFFSET_DID_NOT_OVERFLOW:.*]] = xor i1 %[[COMPUTED_OFFSET_OVERFLOWED]], true, !nosanitize
178177
// CHECK-SANITIZE-NEXT: %[[COMPUTED_GEP_IS_UGE_BASE:.*]] = icmp uge i64 %[[COMPUTED_GEP]], 0, !nosanitize
179178
// CHECK-SANITIZE-NEXT: %[[GEP_DID_NOT_OVERFLOW:.*]] = and i1 %[[COMPUTED_GEP_IS_UGE_BASE]], %[[COMPUTED_OFFSET_DID_NOT_OVERFLOW]], !nosanitize
180-
// CHECK-SANITIZE-NEXT: %[[GEP_IS_OKAY:.*]] = and i1 %[[BOTH_POINTERS_ARE_NULL_OR_BOTH_ARE_NONNULL]], %[[GEP_DID_NOT_OVERFLOW]], !nosanitize
181-
// CHECK-SANITIZE-NEXT: br i1 %[[GEP_IS_OKAY]], label %[[CONT:.*]], label %[[HANDLER_POINTER_OVERFLOW:[^,]+]],{{.*}} !nosanitize
179+
// CHECK-SANITIZE-CPP-NEXT: %[[GEP_IS_OKAY:.*]] = and i1 %[[BOTH_POINTERS_ARE_NULL_OR_BOTH_ARE_NONNULL]], %[[GEP_DID_NOT_OVERFLOW]], !nosanitize
180+
// CHECK-SANITIZE-C-NEXT: br i1 false, label %[[CONT:.*]], label %[[HANDLER_POINTER_OVERFLOW:[^,]+]],{{.*}} !nosanitize
181+
// CHECK-SANITIZE-CPP-NEXT: br i1 %[[GEP_IS_OKAY]], label %[[CONT:.*]], label %[[HANDLER_POINTER_OVERFLOW:[^,]+]],{{.*}} !nosanitize
182182
// CHECK-SANITIZE: [[HANDLER_POINTER_OVERFLOW]]:
183183
// CHECK-SANITIZE-NORECOVER-NEXT: call void @__ubsan_handle_pointer_overflow_abort(i8* bitcast ({ {{{.*}}} }* @[[LINE_500]] to i8*), i64 0, i64 %[[COMPUTED_GEP]])
184184
// CHECK-SANITIZE-RECOVER-NEXT: call void @__ubsan_handle_pointer_overflow(i8* bitcast ({ {{{.*}}} }* @[[LINE_500]] to i8*), i64 0, i64 %[[COMPUTED_GEP]])

‎llvm/include/llvm/IR/IRBuilder.h

Lines changed: 6 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -1362,9 +1362,13 @@ class IRBuilderBase {
13621362
Value *CreateAnd(Value *LHS, Value *RHS, const Twine &Name = "") {
13631363
if (!isa<Constant>(RHS) && isa<Constant>(LHS))
13641364
std::swap(LHS, RHS);
1365-
if (auto *RC = dyn_cast<Constant>(RHS)) {
1366-
if (isa<ConstantInt>(RC) && cast<ConstantInt>(RC)->isMinusOne())
1365+
if (auto RCI = dyn_cast<ConstantInt>(RHS)) {
1366+
if (RCI->isZero())
1367+
return RHS; // LHS & 0 -> 0
1368+
if (RCI->isMinusOne())
13671369
return LHS; // LHS & -1 -> LHS
1370+
}
1371+
if (auto *RC = dyn_cast<Constant>(RHS)) {
13681372
if (auto *LC = dyn_cast<Constant>(LHS))
13691373
return Insert(Folder.CreateAnd(LC, RC), Name);
13701374
}

‎llvm/test/Transforms/LoopPredication/basic.ll

Lines changed: 1 addition & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -1554,12 +1554,11 @@ define i32 @provably_taken(i32* %array, i32* %length.ptr) {
15541554
; CHECK-NEXT: loop.preheader:
15551555
; CHECK-NEXT: [[LENGTH:%.*]] = load i32, i32* [[LENGTH_PTR:%.*]], align 4, !range [[RNG1:![0-9]+]]
15561556
; CHECK-NEXT: [[TMP0:%.*]] = icmp ult i32 0, [[LENGTH]]
1557-
; CHECK-NEXT: [[TMP1:%.*]] = and i1 [[TMP0]], false
15581557
; CHECK-NEXT: br label [[LOOP:%.*]]
15591558
; CHECK: loop:
15601559
; CHECK-NEXT: [[LOOP_ACC:%.*]] = phi i32 [ [[LOOP_ACC_NEXT:%.*]], [[LOOP]] ], [ 0, [[LOOP_PREHEADER:%.*]] ]
15611560
; CHECK-NEXT: [[I:%.*]] = phi i32 [ [[I_NEXT:%.*]], [[LOOP]] ], [ 0, [[LOOP_PREHEADER]] ]
1562-
; CHECK-NEXT: call void (i1, ...) @llvm.experimental.guard(i1 [[TMP1]], i32 9) [ "deopt"() ]
1561+
; CHECK-NEXT: call void (i1, ...) @llvm.experimental.guard(i1 false, i32 9) [ "deopt"() ]
15631562
; CHECK-NEXT: [[I_I64:%.*]] = zext i32 [[I]] to i64
15641563
; CHECK-NEXT: [[ARRAY_I_PTR:%.*]] = getelementptr inbounds i32, i32* [[ARRAY:%.*]], i64 [[I_I64]]
15651564
; CHECK-NEXT: [[ARRAY_I:%.*]] = load i32, i32* [[ARRAY_I_PTR]], align 4

‎llvm/test/Transforms/LoopPredication/reverse.ll

Lines changed: 2 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -123,13 +123,12 @@ define i32 @unsigned_reverse_loop_n_to_0(i32* %array, i32 %length, i32 %n, i32 %
123123
; CHECK: loop.preheader:
124124
; CHECK-NEXT: [[TMP0:%.*]] = add i32 [[N]], -1
125125
; CHECK-NEXT: [[TMP1:%.*]] = icmp ult i32 [[TMP0]], [[LENGTH:%.*]]
126-
; CHECK-NEXT: [[TMP2:%.*]] = and i1 [[TMP1]], false
127126
; CHECK-NEXT: br label [[LOOP:%.*]]
128127
; CHECK: loop:
129128
; CHECK-NEXT: [[LOOP_ACC:%.*]] = phi i32 [ [[LOOP_ACC_NEXT:%.*]], [[LOOP]] ], [ 0, [[LOOP_PREHEADER]] ]
130129
; CHECK-NEXT: [[I:%.*]] = phi i32 [ [[I_NEXT:%.*]], [[LOOP]] ], [ [[N]], [[LOOP_PREHEADER]] ]
131130
; CHECK-NEXT: [[I_NEXT]] = add nsw i32 [[I]], -1
132-
; CHECK-NEXT: call void (i1, ...) @llvm.experimental.guard(i1 [[TMP2]], i32 9) [ "deopt"() ]
131+
; CHECK-NEXT: call void (i1, ...) @llvm.experimental.guard(i1 false, i32 9) [ "deopt"() ]
133132
; CHECK-NEXT: [[I_I64:%.*]] = zext i32 [[I_NEXT]] to i64
134133
; CHECK-NEXT: [[ARRAY_I_PTR:%.*]] = getelementptr inbounds i32, i32* [[ARRAY:%.*]], i64 [[I_I64]]
135134
; CHECK-NEXT: [[ARRAY_I:%.*]] = load i32, i32* [[ARRAY_I_PTR]], align 4
@@ -343,13 +342,12 @@ define i32 @unsigned_reverse_loop_n_to_1(i32* %array, i32 %length, i32 %n, i32 %
343342
; CHECK: loop.preheader:
344343
; CHECK-NEXT: [[TMP0:%.*]] = add i32 [[N]], -1
345344
; CHECK-NEXT: [[TMP1:%.*]] = icmp ult i32 [[TMP0]], [[LENGTH:%.*]]
346-
; CHECK-NEXT: [[TMP2:%.*]] = and i1 [[TMP1]], false
347345
; CHECK-NEXT: br label [[LOOP:%.*]]
348346
; CHECK: loop:
349347
; CHECK-NEXT: [[LOOP_ACC:%.*]] = phi i32 [ [[LOOP_ACC_NEXT:%.*]], [[LOOP]] ], [ 0, [[LOOP_PREHEADER]] ]
350348
; CHECK-NEXT: [[I:%.*]] = phi i32 [ [[I_NEXT:%.*]], [[LOOP]] ], [ [[N]], [[LOOP_PREHEADER]] ]
351349
; CHECK-NEXT: [[I_NEXT]] = add nsw i32 [[I]], -1
352-
; CHECK-NEXT: call void (i1, ...) @llvm.experimental.guard(i1 [[TMP2]], i32 9) [ "deopt"() ]
350+
; CHECK-NEXT: call void (i1, ...) @llvm.experimental.guard(i1 false, i32 9) [ "deopt"() ]
353351
; CHECK-NEXT: [[I_I64:%.*]] = zext i32 [[I_NEXT]] to i64
354352
; CHECK-NEXT: [[ARRAY_I_PTR:%.*]] = getelementptr inbounds i32, i32* [[ARRAY:%.*]], i64 [[I_I64]]
355353
; CHECK-NEXT: [[ARRAY_I:%.*]] = load i32, i32* [[ARRAY_I_PTR]], align 4

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