[llvm] 481db13 - [RISCV] Optimize immediate materialisation with SLLI.UW

[Ben Shi via llvm-commits]

Author: Ben Shi
Date: 2021-10-14T02:24:50Z
New Revision: 481db13fec3d112a23861759247d846f120c6c8b

URL: https://github.com/llvm/llvm-project/commit/481db13fec3d112a23861759247d846f120c6c8b
DIFF: https://github.com/llvm/llvm-project/commit/481db13fec3d112a23861759247d846f120c6c8b.diff

LOG: [RISCV] Optimize immediate materialisation with SLLI.UW

Use LUI+SLLI.UW to compose the upper bits instead of LUI+SLLI.

Reviewed By: craig.topper

Differential Revision: https://reviews.llvm.org/D111705

Added: 
    

Modified: 
    llvm/lib/Target/RISCV/MCTargetDesc/RISCVMatInt.cpp
    llvm/test/CodeGen/RISCV/imm.ll
    llvm/test/MC/RISCV/rv64zba-aliases-valid.s

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Target/RISCV/MCTargetDesc/RISCVMatInt.cpp b/llvm/lib/Target/RISCV/MCTargetDesc/RISCVMatInt.cpp
index 8c0361a4b772b..31c4f67c90b82 100644
--- a/llvm/lib/Target/RISCV/MCTargetDesc/RISCVMatInt.cpp
+++ b/llvm/lib/Target/RISCV/MCTargetDesc/RISCVMatInt.cpp
@@ -106,15 +106,28 @@ static void generateInstSeqImpl(int64_t Val,
 
   // If the remaining bits don't fit in 12 bits, we might be able to reduce the
   // shift amount in order to use LUI which will zero the lower 12 bits.
-  if (ShiftAmount > 12 && !isInt<12>(Hi52) && isInt<32>((uint64_t)Hi52 << 12)) {
-    // Reduce the shift amount and add zeros to the LSBs so it will match LUI.
-    ShiftAmount -= 12;
-    Hi52 = (uint64_t)Hi52 << 12;
+  bool Unsigned = false;
+  if (ShiftAmount > 12 && !isInt<12>(Hi52)) {
+    if (isInt<32>((uint64_t)Hi52 << 12)) {
+      // Reduce the shift amount and add zeros to the LSBs so it will match LUI.
+      ShiftAmount -= 12;
+      Hi52 = (uint64_t)Hi52 << 12;
+    } else if (isUInt<32>((uint64_t)Hi52 << 12) &&
+               ActiveFeatures[RISCV::FeatureStdExtZba]) {
+      // Reduce the shift amount and add zeros to the LSBs so it will match
+      // LUI, then shift left with SLLI.UW to clear the upper 32 set bits.
+      ShiftAmount -= 12;
+      Hi52 = ((uint64_t)Hi52 << 12) | (0xffffffffull << 32);
+      Unsigned = true;
+    }
   }
 
   generateInstSeqImpl(Hi52, ActiveFeatures, Res);
 
-  Res.push_back(RISCVMatInt::Inst(RISCV::SLLI, ShiftAmount));
+  if (Unsigned)
+    Res.push_back(RISCVMatInt::Inst(RISCV::SLLIUW, ShiftAmount));
+  else
+    Res.push_back(RISCVMatInt::Inst(RISCV::SLLI, ShiftAmount));
   if (Lo12)
     Res.push_back(RISCVMatInt::Inst(RISCV::ADDI, Lo12));
 }

diff  --git a/llvm/test/CodeGen/RISCV/imm.ll b/llvm/test/CodeGen/RISCV/imm.ll
index cf8e81c2505af..fa55e8b561a8f 100644
--- a/llvm/test/CodeGen/RISCV/imm.ll
+++ b/llvm/test/CodeGen/RISCV/imm.ll
@@ -928,9 +928,8 @@ define i64 @imm_5372288229() {
 ;
 ; RV64IZBA-LABEL: imm_5372288229:
 ; RV64IZBA:       # %bb.0:
-; RV64IZBA-NEXT:    lui a0, 160
-; RV64IZBA-NEXT:    addiw a0, a0, 437
-; RV64IZBA-NEXT:    slli a0, a0, 13
+; RV64IZBA-NEXT:    lui a0, 655797
+; RV64IZBA-NEXT:    slli.uw a0, a0, 1
 ; RV64IZBA-NEXT:    addi a0, a0, -795
 ; RV64IZBA-NEXT:    ret
 ;
@@ -1563,9 +1562,8 @@ define i64 @imm_12900924131259() {
 ;
 ; RV64IZBA-LABEL: imm_12900924131259:
 ; RV64IZBA:       # %bb.0:
-; RV64IZBA-NEXT:    lui a0, 188
-; RV64IZBA-NEXT:    addiw a0, a0, -1093
-; RV64IZBA-NEXT:    slli a0, a0, 24
+; RV64IZBA-NEXT:    lui a0, 768955
+; RV64IZBA-NEXT:    slli.uw a0, a0, 12
 ; RV64IZBA-NEXT:    addi a0, a0, 1979
 ; RV64IZBA-NEXT:    ret
 ;
@@ -1595,9 +1593,8 @@ define i64 @imm_50394234880() {
 ;
 ; RV64IZBA-LABEL: imm_50394234880:
 ; RV64IZBA:       # %bb.0:
-; RV64IZBA-NEXT:    lui a0, 188
-; RV64IZBA-NEXT:    addiw a0, a0, -1093
-; RV64IZBA-NEXT:    slli a0, a0, 16
+; RV64IZBA-NEXT:    lui a0, 768955
+; RV64IZBA-NEXT:    slli.uw a0, a0, 4
 ; RV64IZBA-NEXT:    ret
 ;
 ; RV64IZBS-LABEL: imm_50394234880:

diff  --git a/llvm/test/MC/RISCV/rv64zba-aliases-valid.s b/llvm/test/MC/RISCV/rv64zba-aliases-valid.s
index 520b5bd706927..3cab2f35e2c19 100644
--- a/llvm/test/MC/RISCV/rv64zba-aliases-valid.s
+++ b/llvm/test/MC/RISCV/rv64zba-aliases-valid.s
@@ -33,20 +33,16 @@ li x6, 0xfffffffe
 # CHECK-S-OBJ-NEXT: zext.w t2, t2
 li x7, 0xaaaaaaaa
 
-# CHECK-S-OBJ-NOALIAS: lui t0, 188
-# CHECK-S-OBJ-NOALIAS-NEXT: addiw t0, t0, -1093
-# CHECK-S-OBJ-NOALIAS-NEXT: slli t0, t0, 24
+# CHECK-S-OBJ-NOALIAS: lui t0, 768955
+# CHECK-S-OBJ-NOALIAS-NEXT: slli.uw t0, t0, 12
 # CHECK-S-OBJ-NOALIAS-NEXT: addi t0, t0, 1979
-# CHECK-S-OBJ: lui t0, 188
-# CHECK-S-OBJ-NEXT: addiw t0, t0, -1093
-# CHECK-S-OBJ-NEXT: slli t0, t0, 24
+# CHECK-S-OBJ: lui t0, 768955
+# CHECK-S-OBJ-NEXT: slli.uw t0, t0, 12
 # CHECK-S-OBJ-NEXT: addi t0, t0, 1979
 li x5, 0xbbbbb0007bb
 
-# CHECK-S-OBJ-NOALIAS: lui t0, 188
-# CHECK-S-OBJ-NOALIAS-NEXT: addiw t0, t0, -1093
-# CHECK-S-OBJ-NOALIAS-NEXT: slli t0, t0, 16
-# CHECK-S-OBJ: lui t0, 188
-# CHECK-S-OBJ-NEXT: addiw t0, t0, -1093
-# CHECK-S-OBJ-NEXT: slli t0, t0, 16
+# CHECK-S-OBJ-NOALIAS: lui t0, 768955
+# CHECK-S-OBJ-NOALIAS-NEXT: slli.uw t0, t0, 4
+# CHECK-S-OBJ: lui t0, 768955
+# CHECK-S-OBJ-NEXT: slli.uw t0, t0, 4
 li x5, 0xbbbbb0000