[RISCV] Optimize immediate materialisation with SH*ADD

[benshi001]

Summary

Use LUI+SH*ADD+ADDI to compose specific immediates.

[craig.topper]

LGTM

[craig.topper]

I accidentally accepted this and I think I can only undo that by selecting Request Changes. Sorry.

llvm/lib/Target/RISCV/MCTargetDesc/RISCVMatInt.cpp

294

Why do we need a cast to uint64_t after the divide?

[benshi001]

llvm/lib/Target/RISCV/MCTargetDesc/RISCVMatInt.cpp

294

the cast to uint64 is removed.

[luismarques]

LGTM.

[benshi001]

In D113568#3123926, @luismarques wrote:

LGTM.

Thanks. Hex values are also attached as comments.

[craig.topper]

LGTM

[kito-cheng]

@benshi001 did you mind take a look for https://github.com/llvm/llvm-project/issues/54812 ?

llvm/lib/Target/RISCV/MCTargetDesc/RISCVMatInt.cpp

if (Res.size() > 2 && ActiveFeatures[RISCV::FeatureStdExtZba]) {
     }
     // Build the new instruction sequence.
     if (Div > 0) {
       generateInstSeqImpl(Val / Div, ActiveFeatures, TmpSeq);
       TmpSeq.push_back(RISCVMatInt::Inst(Opc, 0));
       if (TmpSeq.size() < Res.size())
         Res = TmpSeq;
     }
+    // Try to use LUI+SH*ADD+ADDI.
+    int64_t Hi52 = ((uint64_t)Val + 0x800ull) & ~0xfffull;
+    int64_t Lo12 = SignExtend64<12>(Val);
+    Div = 0;
+    if (isInt<32>(Hi52 / 3) && (Hi52 % 3) == 0) {
+      Div = 3;
+      Opc = RISCV::SH1ADD;
+    } else if (isInt<32>(Hi52 / 5) && (Hi52 % 5) == 0) {
+      Div = 5;
+      Opc = RISCV::SH2ADD;
+    } else if (isInt<32>(Hi52 / 9) && (Hi52 % 9) == 0) {
+      Div = 9;
+      Opc = RISCV::SH3ADD;
+    }
+    // Build the new instruction sequence.
+    if (Div > 0) {
+      // For Val that has zero Lo12 (implies Val equals to Hi52) should has
+      // already been processed to LUI+SH*ADD by previous optimization.
+      assert(Lo12 != 0 &&
+             "unexpected instruction sequence for immediate materialisation");
+      generateInstSeqImpl(Hi52 / Div, ActiveFeatures, TmpSeq);
+      TmpSeq.push_back(RISCVMatInt::Inst(Opc, 0));
+      TmpSeq.push_back(RISCVMatInt::Inst(RISCV::ADDI, Lo12));
+      if (TmpSeq.size() < Res.size())
+        Res = TmpSeq;
+    }
   }
 
   return Res;
 }
 
 int getIntMatCost(const APInt &Val, unsigned Size,
                   const FeatureBitset &ActiveFeatures, bool CompressionCost) {
   bool IsRV64 = ActiveFeatures[RISCV::Feature64Bit];

llvm/test/CodeGen/RISCV/imm.ll

 ; RV64I-NEXT:    lui a0, 427
 ; RV64I-NEXT:    addiw a0, a0, -1367
 ; RV64I-NEXT:    slli a0, a0, 12
 ; RV64I-NEXT:    addi a0, a0, 1
 ; RV64I-NEXT:    ret
 ;
 ; RV64IZBA-LABEL: imm_7158272001:
 ; RV64IZBA:       # %bb.0:
-; RV64IZBA-NEXT:    lui a0, 427
-; RV64IZBA-NEXT:    addiw a0, a0, -1367
-; RV64IZBA-NEXT:    slli a0, a0, 12
+; RV64IZBA-NEXT:    lui a0, 349525
+; RV64IZBA-NEXT:    sh2add a0, a0, a0
 ; RV64IZBA-NEXT:    addi a0, a0, 1
 ; RV64IZBA-NEXT:    ret
 ;
 ; RV64IZBS-LABEL: imm_7158272001:
 ; RV64IZBS:       # %bb.0:
 ; RV64IZBS-NEXT:    lui a0, 427
 ; RV64IZBS-NEXT:    addiw a0, a0, -1367
 ; RV64IZBS-NEXT:    slli a0, a0, 12

 ; RV64I-NEXT:    lui a0, 768
 ; RV64I-NEXT:    addiw a0, a0, -3
 ; RV64I-NEXT:    slli a0, a0, 12
 ; RV64I-NEXT:    addi a0, a0, 1
 ; RV64I-NEXT:    ret
 ;
 ; RV64IZBA-LABEL: imm_12884889601:
 ; RV64IZBA:       # %bb.0:
-; RV64IZBA-NEXT:    lui a0, 768
-; RV64IZBA-NEXT:    addiw a0, a0, -3
-; RV64IZBA-NEXT:    slli a0, a0, 12
+; RV64IZBA-NEXT:    lui a0, 349525
+; RV64IZBA-NEXT:    sh3add a0, a0, a0
 ; RV64IZBA-NEXT:    addi a0, a0, 1
 ; RV64IZBA-NEXT:    ret
 ;
 ; RV64IZBS-LABEL: imm_12884889601:
 ; RV64IZBS:       # %bb.0:
 ; RV64IZBS-NEXT:    lui a0, 768
 ; RV64IZBS-NEXT:    addiw a0, a0, -3
 ; RV64IZBS-NEXT:    slli a0, a0, 12

 ; RV64I-NEXT:    lui a0, 1048371
 ; RV64I-NEXT:    addiw a0, a0, 817
 ; RV64I-NEXT:    slli a0, a0, 12
 ; RV64I-NEXT:    addi a0, a0, 1
 ; RV64I-NEXT:    ret
 ;
 ; RV64IZBA-LABEL: imm_neg_3435982847:
 ; RV64IZBA:       # %bb.0:
-; RV64IZBA-NEXT:    lui a0, 1048371
-; RV64IZBA-NEXT:    addiw a0, a0, 817
-; RV64IZBA-NEXT:    slli a0, a0, 12
+; RV64IZBA-NEXT:    lui a0, 768955
+; RV64IZBA-NEXT:    sh1add a0, a0, a0
 ; RV64IZBA-NEXT:    addi a0, a0, 1
 ; RV64IZBA-NEXT:    ret
 ;
 ; RV64IZBS-LABEL: imm_neg_3435982847:
 ; RV64IZBS:       # %bb.0:
 ; RV64IZBS-NEXT:    lui a0, 734001
 ; RV64IZBS-NEXT:    addiw a0, a0, 1
 ; RV64IZBS-NEXT:    bclri a0, a0, 31

 ; RV64I-NEXT:    lui a0, 1048235
 ; RV64I-NEXT:    addiw a0, a0, -1419
 ; RV64I-NEXT:    slli a0, a0, 12
 ; RV64I-NEXT:    addi a0, a0, 1
 ; RV64I-NEXT:    ret
 ;
 ; RV64IZBA-LABEL: imm_neg_5726842879:
 ; RV64IZBA:       # %bb.0:
-; RV64IZBA-NEXT:    lui a0, 1048235
-; RV64IZBA-NEXT:    addiw a0, a0, -1419
-; RV64IZBA-NEXT:    slli a0, a0, 12
+; RV64IZBA-NEXT:    lui a0, 768945
+; RV64IZBA-NEXT:    sh2add a0, a0, a0
 ; RV64IZBA-NEXT:    addi a0, a0, 1
 ; RV64IZBA-NEXT:    ret
 ;
 ; RV64IZBS-LABEL: imm_neg_5726842879:
 ; RV64IZBS:       # %bb.0:
 ; RV64IZBS-NEXT:    lui a0, 698997
 ; RV64IZBS-NEXT:    addiw a0, a0, 1
 ; RV64IZBS-NEXT:    bclri a0, a0, 32

 ; RV64I-NEXT:    lui a0, 1047962
 ; RV64I-NEXT:    addiw a0, a0, -1645
 ; RV64I-NEXT:    slli a0, a0, 12
 ; RV64I-NEXT:    addi a0, a0, 1
 ; RV64I-NEXT:    ret
 ;
 ; RV64IZBA-LABEL: imm_neg_10307948543:
 ; RV64IZBA:       # %bb.0:
-; RV64IZBA-NEXT:    lui a0, 1047962
-; RV64IZBA-NEXT:    addiw a0, a0, -1645
-; RV64IZBA-NEXT:    slli a0, a0, 12
+; RV64IZBA-NEXT:    lui a0, 768955
+; RV64IZBA-NEXT:    sh3add a0, a0, a0
 ; RV64IZBA-NEXT:    addi a0, a0, 1
 ; RV64IZBA-NEXT:    ret
 ;
 ; RV64IZBS-LABEL: imm_neg_10307948543:
 ; RV64IZBS:       # %bb.0:
 ; RV64IZBS-NEXT:    lui a0, 629139
 ; RV64IZBS-NEXT:    addiw a0, a0, 1
 ; RV64IZBS-NEXT:    bclri a0, a0, 33
 ; RV64IZBS-NEXT:    ret
   ret i64 -10307948543 ; 0xffff_fffd_9999_3001
 }

llvm/test/MC/RISCV/rv64zba-aliases-valid.s

 # CHECK-S-OBJ-NOALIAS-NEXT: slli.uw t1, t1, 12
 # CHECK-S-OBJ-NOALIAS-NEXT: addi t1, t1, -1366
 # CHECK-S-OBJ: lui t1, 768955
 # CHECK-S-OBJ-NEXT: addiw t1, t1, -1365
 # CHECK-S-OBJ-NEXT: slli.uw t1, t1, 12
 # CHECK-S-OBJ-NEXT: addi t1, t1, -1366
 li x6, 12900918536874
 
-# CHECK-S-OBJ-NOALIAS: lui t1, 427
-# CHECK-S-OBJ-NOALIAS-NEXT: addiw t1, t1, -1367
-# CHECK-S-OBJ-NOALIAS-NEXT: slli t1, t1, 12
+# CHECK-S-OBJ-NOALIAS: lui t1, 349525
+# CHECK-S-OBJ-NOALIAS-NEXT: sh2add t1, t1, t1
 # CHECK-S-OBJ-NOALIAS-NEXT: addi t1, t1, 1
-# CHECK-S-OBJ: lui t1, 427
-# CHECK-S-OBJ-NEXT: addiw t1, t1, -1367
-# CHECK-S-OBJ-NEXT: slli t1, t1, 12
+# CHECK-S-OBJ: lui t1, 349525
+# CHECK-S-OBJ-NEXT: sh2add t1, t1, t1
 # CHECK-S-OBJ-NEXT: addi t1, t1, 1
 li x6, 7158272001 # 0x0000_0001_aaaa_9001
 
-# CHECK-S-OBJ-NOALIAS: lui t1, 768
-# CHECK-S-OBJ-NOALIAS-NEXT: addiw t1, t1, -3
-# CHECK-S-OBJ-NOALIAS-NEXT: slli t1, t1, 12
+# CHECK-S-OBJ-NOALIAS: lui t1, 349525
+# CHECK-S-OBJ-NOALIAS-NEXT: sh3add t1, t1, t1
 # CHECK-S-OBJ-NOALIAS-NEXT: addi t1, t1, 1
-# CHECK-S-OBJ: lui t1, 768
-# CHECK-S-OBJ-NEXT: addiw t1, t1, -3
-# CHECK-S-OBJ-NEXT: slli t1, t1, 12
+# CHECK-S-OBJ: lui t1, 349525
+# CHECK-S-OBJ-NEXT: sh3add t1, t1, t1
 # CHECK-S-OBJ-NEXT: addi t1, t1, 1
 li x6, 12884889601 # 0x0000_0002_ffff_d001
 
-# CHECK-S-OBJ-NOALIAS: lui t1, 1048371
-# CHECK-S-OBJ-NOALIAS-NEXT: addiw t1, t1, 817
-# CHECK-S-OBJ-NOALIAS-NEXT: slli t1, t1, 12
+# CHECK-S-OBJ-NOALIAS: lui t1, 768955
+# CHECK-S-OBJ-NOALIAS-NEXT: sh1add t1, t1, t1
 # CHECK-S-OBJ-NOALIAS-NEXT: addi t1, t1, 1
-# CHECK-S-OBJ: lui t1, 1048371
-# CHECK-S-OBJ-NEXT: addiw t1, t1, 817
-# CHECK-S-OBJ-NEXT: slli t1, t1, 12
+# CHECK-S-OBJ: lui t1, 768955
+# CHECK-S-OBJ-NEXT: sh1add t1, t1, t1
 # CHECK-S-OBJ-NEXT: addi t1, t1, 1
 li x6, -3435982847 # 0xffff_ffff_3333_1001
 
-# CHECK-S-OBJ-NOALIAS: lui t1, 1048235
-# CHECK-S-OBJ-NOALIAS-NEXT: addiw t1, t1, -1419
-# CHECK-S-OBJ-NOALIAS-NEXT: slli t1, t1, 12
+# CHECK-S-OBJ-NOALIAS: lui t1, 768945
+# CHECK-S-OBJ-NOALIAS-NEXT: sh2add t1, t1, t1
 # CHECK-S-OBJ-NOALIAS-NEXT: addi t1, t1, 1
-# CHECK-S-OBJ: lui t1, 1048235
-# CHECK-S-OBJ-NEXT: addiw t1, t1, -1419
-# CHECK-S-OBJ-NEXT: slli t1, t1, 12
+# CHECK-S-OBJ: lui t1, 768945
+# CHECK-S-OBJ-NEXT: sh2add t1, t1, t1
 # CHECK-S-OBJ-NEXT: addi t1, t1, 1
 li x6, -5726842879 # 0xffff_fffe_aaa7_5001
 
-# CHECK-S-OBJ-NOALIAS: lui t1, 1047962
-# CHECK-S-OBJ-NOALIAS-NEXT: addiw t1, t1, -1645
-# CHECK-S-OBJ-NOALIAS-NEXT: slli t1, t1, 12
+# CHECK-S-OBJ-NOALIAS: lui t1, 768955
+# CHECK-S-OBJ-NOALIAS-NEXT: sh3add t1, t1, t1
 # CHECK-S-OBJ-NOALIAS-NEXT: addi t1, t1, 1
-# CHECK-S-OBJ: lui t1, 1047962
-# CHECK-S-OBJ-NEXT: addiw t1, t1, -1645
-# CHECK-S-OBJ-NEXT: slli t1, t1, 12
+# CHECK-S-OBJ: lui t1, 768955
+# CHECK-S-OBJ-NEXT: sh3add t1, t1, t1
 # CHECK-S-OBJ-NEXT: addi t1, t1, 1
 li x6, -10307948543 # 0xffff_fffd_9999_3001