SmallVector<SDValue, 16> ConstLanes;
for (const SDValue &Lane : Op->op_values()) {
if (IsConstant(Lane)) {
- ConstLanes.push_back(Lane);
+ // Values may need to be fixed so that they will sign extend to be
+ // within the expected range during ISel. Check whether the value is in
+ // bounds based on the lane bit width and if it is out of bounds, lop
+ // off the extra bits and subtract 2^n to reflect giving the high bit
+ // value -2^(n-1) rather than +2^(n-1). Skip the i64 case because it
+ // cannot possibly be out of range.
+ auto *Const = dyn_cast<ConstantSDNode>(Lane.getNode());
+ int64_t Val = Const ? Const->getSExtValue() : 0;
+ uint64_t LaneBits = 128 / Lanes;
+ assert((LaneT == MVT::i64 || Val >= -(1 << (LaneBits - 1))) &&
+ "Unexpected out of bounds negative value");
+ if (Const && LaneT != MVT::i64 && Val > (1 << (LaneBits - 1)) - 1) {
+ auto NewVal = ((uint64_t)Val % (1u << LaneBits)) - (1u << LaneBits);
+ ConstLanes.push_back(DAG.getConstant(NewVal, SDLoc(Lane), LaneT));
+ } else {
+ ConstLanes.push_back(Lane);
+ }
} else if (LaneT.isFloatingPoint()) {
ConstLanes.push_back(DAG.getConstantFP(0, DL, LaneT));
} else {
--- /dev/null
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
+; RUN: llc < %s -verify-machineinstrs -mattr=+simd128 | FileCheck %s
+
+; Regression test for an issue in which DAG combines created a constant i8x16
+; vector with lane values of 255, which was outside the -128 to 127 range
+; expected by our ISel patterns (and similar for the i16 version) and caused an
+; ISel failure. The fix was to adjust out-of-range values manually in
+; BUILD_VECTOR lowering.
+
+target triple = "wasm32-unknown-unknown"
+
+define <4 x i8> @test_i8(<4 x i8> %b) {
+; CHECK-LABEL: test_i8:
+; CHECK: .functype test_i8 (v128) -> (v128)
+; CHECK-NEXT: # %bb.0:
+; CHECK-NEXT: local.get 0
+; CHECK-NEXT: v128.const -1, -1, -1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
+; CHECK-NEXT: v128.xor
+; CHECK-NEXT: v128.const 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
+; CHECK-NEXT: v128.and
+; CHECK-NEXT: # fallthrough-return
+ %c = and <4 x i8> %b, <i8 1, i8 1, i8 1, i8 1>
+ %d = xor <4 x i8> %c, <i8 1, i8 1, i8 1, i8 1>
+ ret <4 x i8> %d
+}
+
+define <4 x i16> @test_i16(<4 x i16> %b) {
+; CHECK-LABEL: test_i16:
+; CHECK: .functype test_i16 (v128) -> (v128)
+; CHECK-NEXT: # %bb.0:
+; CHECK-NEXT: local.get 0
+; CHECK-NEXT: v128.const -1, -1, -1, -1, 0, 0, 0, 0
+; CHECK-NEXT: v128.xor
+; CHECK-NEXT: v128.const 1, 1, 1, 1, 0, 0, 0, 0
+; CHECK-NEXT: v128.and
+; CHECK-NEXT: # fallthrough-return
+ %c = and <4 x i16> %b, <i16 1, i16 1, i16 1, i16 1>
+ %d = xor <4 x i16> %c, <i16 1, i16 1, i16 1, i16 1>
+ ret <4 x i16> %d
+}