[DAG] canCreateUndefOrPoison - remove AssertSext/AssertZext assumption that they never create undef/poison

We need to assume that we generate poison if the assertions failed

Fixes #66603

Author: RKSimon

llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp

@@ -5011,8 +5011,6 @@ bool SelectionDAG::canCreateUndefOrPoison(SDValue Op, const APInt &DemandedElts,
 
   unsigned Opcode = Op.getOpcode();
   switch (Opcode) {
-  case ISD::AssertSext:
-  case ISD::AssertZext:
   case ISD::FREEZE:
   case ISD::CONCAT_VECTORS:
   case ISD::INSERT_SUBVECTOR:

llvm/test/CodeGen/AArch64/pr66603.ll

@@ -1,10 +1,12 @@
 ; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --version 3
 ; RUN: llc < %s -mtriple=aarch64-- -verify-machineinstrs | FileCheck %s
 
+; Don't fold freeze(assertsext(x)) -> assertsext(freeze(x))
 define i32 @PR66603(double %x) nounwind {
 ; CHECK-LABEL: PR66603:
 ; CHECK:       // %bb.0:
-; CHECK-NEXT:    fcvtzs w0, d0
+; CHECK-NEXT:    fcvtzs w8, d0
+; CHECK-NEXT:    sxtb w0, w8
 ; CHECK-NEXT:    ret
   %as_i8 = fptosi double %x to i8
   %frozen_i8 = freeze i8 %as_i8

llvm/test/CodeGen/RISCV/pr66603.ll

@@ -2,15 +2,20 @@
 ; RUN: llc < %s -mtriple=riscv32-- -mattr=+d -verify-machineinstrs | FileCheck %s -check-prefix=RV32
 ; RUN: llc < %s -mtriple=riscv64-- -mattr=+d -verify-machineinstrs | FileCheck %s -check-prefix=RV64
 
+; Don't fold freeze(assertsext(x)) -> assertsext(freeze(x))
 define i32 @PR66603(double %x) nounwind {
 ; RV32-LABEL: PR66603:
 ; RV32:       # %bb.0:
 ; RV32-NEXT:    fcvt.w.d a0, fa0, rtz
+; RV32-NEXT:    slli a0, a0, 24
+; RV32-NEXT:    srai a0, a0, 24
 ; RV32-NEXT:    ret
 ;
 ; RV64-LABEL: PR66603:
 ; RV64:       # %bb.0:
 ; RV64-NEXT:    fcvt.l.d a0, fa0, rtz
+; RV64-NEXT:    slli a0, a0, 56
+; RV64-NEXT:    srai a0, a0, 56
 ; RV64-NEXT:    ret
   %as_i8 = fptosi double %x to i8
   %frozen_i8 = freeze i8 %as_i8

llvm/test/CodeGen/RISCV/rv64zbb.ll

@@ -1422,7 +1422,7 @@ define i32 @abs_i32(i32 %x) {
 define signext i32 @abs_i32_sext(i32 signext %x) {
 ; RV64I-LABEL: abs_i32_sext:
 ; RV64I:       # %bb.0:
-; RV64I-NEXT:    srai a1, a0, 31
+; RV64I-NEXT:    sraiw a1, a0, 31
 ; RV64I-NEXT:    xor a0, a0, a1
 ; RV64I-NEXT:    subw a0, a0, a1
 ; RV64I-NEXT:    ret