[PATCH] D140928: [RISCV] Prevent constant hoisting for or/and/xor that can use bseti/bclri/binvi.

[Craig Topper via Phabricator via llvm-commits]

craig.topper created this revision.
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Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D140928

Files:
  llvm/lib/Target/RISCV/RISCVTargetTransformInfo.cpp
  llvm/test/Transforms/ConstantHoisting/RISCV/immediates.ll


Index: llvm/test/Transforms/ConstantHoisting/RISCV/immediates.ll
===================================================================
--- llvm/test/Transforms/ConstantHoisting/RISCV/immediates.ll
+++ llvm/test/Transforms/ConstantHoisting/RISCV/immediates.ll
@@ -95,3 +95,30 @@
   %5 = mul i32 %2, %4
   ret i32 %5
 }
+
+; bseti
+define i64 @test11(i64 %a) nounwind "target-features"="+zbs" {
+; CHECK-LABEL: test11
+; CHECK: or i64 %a, 8589934592
+  %1 = or i64 %a, 8589934592 ; 1 << 33
+  %2 = or i64 %1, 8589934592 ; 1 << 33
+  ret i64 %2
+}
+
+; binvi
+define i64 @test12(i64 %a) nounwind "target-features"="+zbs" {
+; CHECK-LABEL: test12
+; CHECK: xor i64 %a, -9223372036854775808
+  %1 = xor i64 %a, -9223372036854775808 ; 1 << 63
+  %2 = xor i64 %1, -9223372036854775808 ; 1 << 63
+  ret i64 %2
+}
+
+; bclri
+define i64 @test13(i64 %a) nounwind "target-features"="+zbs" {
+; CHECK-LABEL: test13
+; CHECK: and i64 %a, -281474976710657
+  %1 = and i64 %a, -281474976710657 ; ~(1 << 48)
+  %2 = and i64 %1, -281474976710657 ; ~(1 << 48)
+  ret i64 %2
+}
Index: llvm/lib/Target/RISCV/RISCVTargetTransformInfo.cpp
===================================================================
--- llvm/lib/Target/RISCV/RISCVTargetTransformInfo.cpp
+++ llvm/lib/Target/RISCV/RISCVTargetTransformInfo.cpp
@@ -124,13 +124,22 @@
     // zext.w
     if (Imm == UINT64_C(0xffffffff) && ST->hasStdExtZba())
       return TTI::TCC_Free;
+    // bclri
+    if (ST->hasStdExtZbs() && (~Imm).isPowerOf2())
+      return TTI::TCC_Free;
     if (Inst && Idx == 1 && Imm.getBitWidth() <= ST->getXLen() &&
         canUseShiftPair(Inst, Imm))
       return TTI::TCC_Free;
-    [[fallthrough]];
+    Takes12BitImm = true;
+    break;
   case Instruction::Add:
+    Takes12BitImm = true;
+    break;
   case Instruction::Or:
   case Instruction::Xor:
+    // bseti/binvi
+    if (ST->hasStdExtZbs() && Imm.isPowerOf2())
+      return TTI::TCC_Free;
     Takes12BitImm = true;
     break;
   case Instruction::Mul:


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