[RISCV] Change zext.w to be an alias of add.uw rd, rs1, x0 instead of pack.

This didn't make it into the published 0.93 spec, but it was the
intention.

But it is in the tex source as of this commit
d172f029c0

This means zext.w now requires Zba. Not sure if we should still use
pack if Zbp is enabled and Zba isn't. I'll leave that for the future
when pack is closer to being final.

Reviewed By: asb, frasercrmck

Differential Revision: https://reviews.llvm.org/D94736

llvm/lib/Target/RISCV/RISCV.td

@@ -62,6 +62,7 @@ def FeatureExtZba
 def HasStdExtZba : Predicate<"Subtarget->hasStdExtZba()">,
                              AssemblerPredicate<(all_of FeatureExtZba),
                              "'Zba' (Address calculation 'B' Instructions)">;
+def NotHasStdExtZba : Predicate<"!Subtarget->hasStdExtZba()">;
 
 def FeatureExtZbb
     : SubtargetFeature<"experimental-zbb", "HasStdExtZbb", "true",
@@ -131,8 +132,6 @@ def HasStdExtZbt : Predicate<"Subtarget->hasStdExtZbt()">,
 def HasStdExtZbbOrZbp
     : Predicate<"Subtarget->hasStdExtZbb() || Subtarget->hasStdExtZbp()">,
                 AssemblerPredicate<(any_of FeatureExtZbb, FeatureExtZbp)>;
-def NotHasStdExtZbbOrZbp
-    : Predicate<"!(Subtarget->hasStdExtZbb() || Subtarget->hasStdExtZbp())">;
 
 def FeatureExtZbproposedc
     : SubtargetFeature<"experimental-zbproposedc", "HasStdExtZbproposedc", "true",

llvm/lib/Target/RISCV/RISCVInstrInfo.td

@@ -1158,7 +1158,7 @@ def ADJCALLSTACKUP   : Pseudo<(outs), (ins i32imm:$amt1, i32imm:$amt2),
 
 /// RV64 patterns
 
-let Predicates = [IsRV64, NotHasStdExtZbbOrZbp] in
+let Predicates = [IsRV64, NotHasStdExtZba] in
 def : Pat<(and GPR:$rs1, 0xffffffff), (SRLI (SLLI GPR:$rs1, 32), 32)>;
 
 let Predicates = [IsRV64] in {

llvm/lib/Target/RISCV/RISCVInstrInfoB.td

@@ -495,7 +495,7 @@ def C_NOT : RVBInstC<0b00, "c.not">, Sched<[]>;
 def C_NEG : RVBInstC<0b01, "c.neg">, Sched<[]>;
 } // DecoderNamespace = "RVBC", Predicates = [HasStdExtZbproposedc, HasStdExtC]
 
-let DecoderNamespace = "RVBC", Predicates = [HasStdExtZbproposedc, HasStdExtZbbOrZbp, HasStdExtC, IsRV64] in
+let DecoderNamespace = "RVBC", Predicates = [HasStdExtZbproposedc, HasStdExtZba, HasStdExtC, IsRV64] in
 def C_ZEXTW : RVBInstC<0b10, "c.zext.w">, Sched<[]>;
 
 //===----------------------------------------------------------------------===//
@@ -508,9 +508,14 @@ def : InstAlias<"zext.h $rd, $rs", (PACK GPR:$rd, GPR:$rs, X0)>;
 
 let Predicates = [HasStdExtZbb, IsRV64] in {
 def : InstAlias<"zext.h $rd, $rs", (PACKW GPR:$rd, GPR:$rs, X0)>;
-def : InstAlias<"zext.w $rd, $rs", (PACK GPR:$rd, GPR:$rs, X0)>;
 } // Predicates = [HasStdExtZbb, IsRV64]
 
+let Predicates = [HasStdExtZba, IsRV64] in {
+// NOTE: The 0.93 spec shows zext.w as an alias of pack/packw. It has been
+// changed to add.uw in a draft after 0.94.
+def : InstAlias<"zext.w $rd, $rs", (ADDUW GPR:$rd, GPR:$rs, X0)>;
+}
+
 let Predicates = [HasStdExtZbp] in {
 def : InstAlias<"rev.p $rd, $rs",  (GREVI GPR:$rd, GPR:$rs, 0b00001)>;
 def : InstAlias<"rev2.n $rd, $rs", (GREVI GPR:$rd, GPR:$rs, 0b00010)>;
@@ -626,8 +631,8 @@ def : CompressPat<(SUB GPRC:$rs1, X0, GPRC:$rs1),
                   (C_NEG GPRC:$rs1)>;
 } // Predicates = [HasStdExtZbproposedc, HasStdExtC]
 
-let Predicates = [HasStdExtZbproposedc, HasStdExtZbbOrZbp, HasStdExtC, IsRV64] in {
+let Predicates = [HasStdExtZbproposedc, HasStdExtZba, HasStdExtC, IsRV64] in {
-def : CompressPat<(PACK GPRC:$rs1, GPRC:$rs1, X0),
+def : CompressPat<(ADDUW GPRC:$rs1, GPRC:$rs1, X0),
                   (C_ZEXTW GPRC:$rs1)>;
 } // Predicates = [HasStdExtZbproposedc, HasStdExtC, IsRV64]
 
@@ -806,7 +811,6 @@ let Predicates = [HasStdExtZbbOrZbp, IsRV32] in
 def : Pat<(and GPR:$rs, 0x0000FFFF), (PACK GPR:$rs, X0)>;
 let Predicates = [HasStdExtZbbOrZbp, IsRV64] in {
 def : Pat<(and GPR:$rs, 0x000000000000FFFF), (PACKW GPR:$rs, X0)>;
-def : Pat<(and GPR:$rs, 0x00000000FFFFFFFF), (PACK GPR:$rs, X0)>;
 }
 
 let Predicates = [HasStdExtZbp, IsRV32] in {
@@ -858,6 +862,7 @@ def : Pat<(shl (and GPR:$rs1, 0xFFFFFFFF), uimm5:$shamt),
           (SLLIUW GPR:$rs1, uimm5:$shamt)>;
 def : Pat<(add (and GPR:$rs1, (i64 0xFFFFFFFF)), GPR:$rs2),
           (ADDUW GPR:$rs1, GPR:$rs2)>;
+def : Pat<(and GPR:$rs, 0x00000000FFFFFFFF), (ADDUW GPR:$rs, X0)>;
 }
 
 let Predicates = [HasStdExtZbp, IsRV64] in {

llvm/test/CodeGen/RISCV/rv64Zba.ll

@@ -109,3 +109,23 @@ define signext i8 @adduw_2(i32 signext %0, i8* %1) {
   %5 = load i8, i8* %4
   ret i8 %5
 }
+
+define i64 @zextw_i64(i64 %a) nounwind {
+; RV64I-LABEL: zextw_i64:
+; RV64I:       # %bb.0:
+; RV64I-NEXT:    slli a0, a0, 32
+; RV64I-NEXT:    srli a0, a0, 32
+; RV64I-NEXT:    ret
+;
+; RV64IB-LABEL: zextw_i64:
+; RV64IB:       # %bb.0:
+; RV64IB-NEXT:    zext.w a0, a0
+; RV64IB-NEXT:    ret
+;
+; RV64IBA-LABEL: zextw_i64:
+; RV64IBA:       # %bb.0:
+; RV64IBA-NEXT:    zext.w a0, a0
+; RV64IBA-NEXT:    ret
+  %and = and i64 %a, 4294967295
+  ret i64 %and
+}

llvm/test/CodeGen/RISCV/rv64Zbbp.ll

@@ -792,28 +792,3 @@ define i64 @packh_i64(i64 %a, i64 %b) nounwind {
   %or = or i64 %shl, %and
   ret i64 %or
 }
-
-define i64 @zextw_i64(i64 %a) nounwind {
-; RV64I-LABEL: zextw_i64:
-; RV64I:       # %bb.0:
-; RV64I-NEXT:    slli a0, a0, 32
-; RV64I-NEXT:    srli a0, a0, 32
-; RV64I-NEXT:    ret
-;
-; RV64IB-LABEL: zextw_i64:
-; RV64IB:       # %bb.0:
-; RV64IB-NEXT:    zext.w a0, a0
-; RV64IB-NEXT:    ret
-;
-; RV64IBB-LABEL: zextw_i64:
-; RV64IBB:       # %bb.0:
-; RV64IBB-NEXT:    zext.w a0, a0
-; RV64IBB-NEXT:    ret
-;
-; RV64IBP-LABEL: zextw_i64:
-; RV64IBP:       # %bb.0:
-; RV64IBP-NEXT:    pack a0, a0, zero
-; RV64IBP-NEXT:    ret
-  %and = and i64 %a, 4294967295
-  ret i64 %and
-}

llvm/test/MC/RISCV/rv64b-aliases-valid.s

@@ -23,7 +23,7 @@ zext.b x5, x6
 # CHECK-S-OBJ: zext.h t0, t1
 zext.h x5, x6
 
-# CHECK-S-OBJ-NOALIAS: pack t0, t1, zero
+# CHECK-S-OBJ-NOALIAS: add.uw t0, t1, zero
 # CHECK-S-OBJ: zext.w t0, t1
 zext.w x5, x6