[RISCV] Optimize multiplication with immediates

The optimization of (mul x, c) to (ADD (SLLI x, i0), (SLLI x, i1))
is only enabled for i32 multiplication on rv64, because of
the regression in i64 multiplication on rv32.

However we can change the condition to that the immediate 'c'
should only be used once, then the above regression can also be
avoided, and ohter chances of optimization can be enabled.

Reviewed By: craig.topper

Differential Revision: https://reviews.llvm.org/D147410

diff --git a/llvm/lib/Target/RISCV/RISCVISelLowering.cpp b/llvm/lib/Target/RISCV/RISCVISelLowering.cpp
index 94c4222..7641c0f 100644 (file)
--- a/llvm/lib/Target/RISCV/RISCVISelLowering.cpp
+++ b/llvm/lib/Target/RISCV/RISCVISelLowering.cpp
@@ -15253,13 +15253,10 @@ bool RISCVTargetLowering::decomposeMulByConstant(LLVMContext &Context, EVT VT,
           ((Imm - 2).isPowerOf2() || (Imm - 4).isPowerOf2() ||
            (Imm - 8).isPowerOf2()))
         return true;
-      // Omit the following optimization if the sub target has the M extension
-      // and the data size >= XLen.
-      if (HasExtMOrZmmul && VT.getSizeInBits() >= Subtarget.getXLen())
-        return false;
       // Break the MUL to two SLLI instructions and an ADD/SUB, if Imm needs
       // a pair of LUI/ADDI.
-      if (!Imm.isSignedIntN(12) && Imm.countr_zero() < 12) {
+      if (!Imm.isSignedIntN(12) && Imm.countr_zero() < 12 &&
+          ConstNode->hasOneUse()) {
         APInt ImmS = Imm.ashr(Imm.countr_zero());
         if ((ImmS + 1).isPowerOf2() || (ImmS - 1).isPowerOf2() ||
             (1 - ImmS).isPowerOf2())

diff --git a/llvm/test/CodeGen/RISCV/mul.ll b/llvm/test/CodeGen/RISCV/mul.ll
index 31843f5..49c8d16 100644 (file)
--- a/llvm/test/CodeGen/RISCV/mul.ll
+++ b/llvm/test/CodeGen/RISCV/mul.ll
@@ -819,9 +819,9 @@ define i32 @muli32_p4352(i32 %a) nounwind {
 ;
 ; RV32IM-LABEL: muli32_p4352:
 ; RV32IM:       # %bb.0:
-; RV32IM-NEXT:    li a1, 17
-; RV32IM-NEXT:    slli a1, a1, 8
-; RV32IM-NEXT:    mul a0, a0, a1
+; RV32IM-NEXT:    slli a1, a0, 8
+; RV32IM-NEXT:    slli a0, a0, 12
+; RV32IM-NEXT:    add a0, a0, a1
 ; RV32IM-NEXT:    ret
 ;
 ; RV64I-LABEL: muli32_p4352:
@@ -851,9 +851,9 @@ define i32 @muli32_p3840(i32 %a) nounwind {
 ;
 ; RV32IM-LABEL: muli32_p3840:
 ; RV32IM:       # %bb.0:
-; RV32IM-NEXT:    li a1, 15
-; RV32IM-NEXT:    slli a1, a1, 8
-; RV32IM-NEXT:    mul a0, a0, a1
+; RV32IM-NEXT:    slli a1, a0, 8
+; RV32IM-NEXT:    slli a0, a0, 12
+; RV32IM-NEXT:    sub a0, a0, a1
 ; RV32IM-NEXT:    ret
 ;
 ; RV64I-LABEL: muli32_p3840:
@@ -883,9 +883,9 @@ define i32 @muli32_m3840(i32 %a) nounwind {
 ;
 ; RV32IM-LABEL: muli32_m3840:
 ; RV32IM:       # %bb.0:
-; RV32IM-NEXT:    li a1, -15
-; RV32IM-NEXT:    slli a1, a1, 8
-; RV32IM-NEXT:    mul a0, a0, a1
+; RV32IM-NEXT:    slli a1, a0, 12
+; RV32IM-NEXT:    slli a0, a0, 8
+; RV32IM-NEXT:    sub a0, a0, a1
 ; RV32IM-NEXT:    ret
 ;
 ; RV64I-LABEL: muli32_m3840:
@@ -976,9 +976,9 @@ define i64 @muli64_p4352(i64 %a) nounwind {
 ;
 ; RV64IM-LABEL: muli64_p4352:
 ; RV64IM:       # %bb.0:
-; RV64IM-NEXT:    li a1, 17
-; RV64IM-NEXT:    slli a1, a1, 8
-; RV64IM-NEXT:    mul a0, a0, a1
+; RV64IM-NEXT:    slli a1, a0, 8
+; RV64IM-NEXT:    slli a0, a0, 12
+; RV64IM-NEXT:    add a0, a0, a1
 ; RV64IM-NEXT:    ret
   %1 = mul i64 %a, 4352
   ret i64 %1
@@ -1020,9 +1020,9 @@ define i64 @muli64_p3840(i64 %a) nounwind {
 ;
 ; RV64IM-LABEL: muli64_p3840:
 ; RV64IM:       # %bb.0:
-; RV64IM-NEXT:    li a1, 15
-; RV64IM-NEXT:    slli a1, a1, 8
-; RV64IM-NEXT:    mul a0, a0, a1
+; RV64IM-NEXT:    slli a1, a0, 8
+; RV64IM-NEXT:    slli a0, a0, 12
+; RV64IM-NEXT:    sub a0, a0, a1
 ; RV64IM-NEXT:    ret
   %1 = mul i64 %a, 3840
   ret i64 %1
@@ -1105,9 +1105,9 @@ define i64 @muli64_m3840(i64 %a) nounwind {
 ;
 ; RV64IM-LABEL: muli64_m3840:
 ; RV64IM:       # %bb.0:
-; RV64IM-NEXT:    li a1, -15
-; RV64IM-NEXT:    slli a1, a1, 8
-; RV64IM-NEXT:    mul a0, a0, a1
+; RV64IM-NEXT:    slli a1, a0, 12
+; RV64IM-NEXT:    slli a0, a0, 8
+; RV64IM-NEXT:    sub a0, a0, a1
 ; RV64IM-NEXT:    ret
   %1 = mul i64 %a, -3840
   ret i64 %1

diff --git a/llvm/test/CodeGen/RISCV/rv32zba.ll b/llvm/test/CodeGen/RISCV/rv32zba.ll
index b29ef39..0908a39 100644 (file)
--- a/llvm/test/CodeGen/RISCV/rv32zba.ll
+++ b/llvm/test/CodeGen/RISCV/rv32zba.ll
@@ -479,9 +479,9 @@ define i32 @mul81(i32 %a) {
 define i32 @mul4098(i32 %a) {
 ; RV32I-LABEL: mul4098:
 ; RV32I:       # %bb.0:
-; RV32I-NEXT:    lui a1, 1
-; RV32I-NEXT:    addi a1, a1, 2
-; RV32I-NEXT:    mul a0, a0, a1
+; RV32I-NEXT:    slli a1, a0, 1
+; RV32I-NEXT:    slli a0, a0, 12
+; RV32I-NEXT:    add a0, a0, a1
 ; RV32I-NEXT:    ret
 ;
 ; RV32ZBA-LABEL: mul4098:
@@ -496,9 +496,9 @@ define i32 @mul4098(i32 %a) {
 define i32 @mul4100(i32 %a) {
 ; RV32I-LABEL: mul4100:
 ; RV32I:       # %bb.0:
-; RV32I-NEXT:    lui a1, 1
-; RV32I-NEXT:    addi a1, a1, 4
-; RV32I-NEXT:    mul a0, a0, a1
+; RV32I-NEXT:    slli a1, a0, 2
+; RV32I-NEXT:    slli a0, a0, 12
+; RV32I-NEXT:    add a0, a0, a1
 ; RV32I-NEXT:    ret
 ;
 ; RV32ZBA-LABEL: mul4100:
@@ -513,9 +513,9 @@ define i32 @mul4100(i32 %a) {
 define i32 @mul4104(i32 %a) {
 ; RV32I-LABEL: mul4104:
 ; RV32I:       # %bb.0:
-; RV32I-NEXT:    lui a1, 1
-; RV32I-NEXT:    addi a1, a1, 8
-; RV32I-NEXT:    mul a0, a0, a1
+; RV32I-NEXT:    slli a1, a0, 3
+; RV32I-NEXT:    slli a0, a0, 12
+; RV32I-NEXT:    add a0, a0, a1
 ; RV32I-NEXT:    ret
 ;
 ; RV32ZBA-LABEL: mul4104:

diff --git a/llvm/test/CodeGen/RISCV/rv64zba.ll b/llvm/test/CodeGen/RISCV/rv64zba.ll
index d89d588..2f82d56 100644 (file)
--- a/llvm/test/CodeGen/RISCV/rv64zba.ll
+++ b/llvm/test/CodeGen/RISCV/rv64zba.ll
@@ -986,9 +986,9 @@ define i64 @mul81(i64 %a) {
 define i64 @mul4098(i64 %a) {
 ; RV64I-LABEL: mul4098:
 ; RV64I:       # %bb.0:
-; RV64I-NEXT:    lui a1, 1
-; RV64I-NEXT:    addiw a1, a1, 2
-; RV64I-NEXT:    mul a0, a0, a1
+; RV64I-NEXT:    slli a1, a0, 1
+; RV64I-NEXT:    slli a0, a0, 12
+; RV64I-NEXT:    add a0, a0, a1
 ; RV64I-NEXT:    ret
 ;
 ; RV64ZBA-LABEL: mul4098:
@@ -1003,9 +1003,9 @@ define i64 @mul4098(i64 %a) {
 define i64 @mul4100(i64 %a) {
 ; RV64I-LABEL: mul4100:
 ; RV64I:       # %bb.0:
-; RV64I-NEXT:    lui a1, 1
-; RV64I-NEXT:    addiw a1, a1, 4
-; RV64I-NEXT:    mul a0, a0, a1
+; RV64I-NEXT:    slli a1, a0, 2
+; RV64I-NEXT:    slli a0, a0, 12
+; RV64I-NEXT:    add a0, a0, a1
 ; RV64I-NEXT:    ret
 ;
 ; RV64ZBA-LABEL: mul4100:
@@ -1020,9 +1020,9 @@ define i64 @mul4100(i64 %a) {
 define i64 @mul4104(i64 %a) {
 ; RV64I-LABEL: mul4104:
 ; RV64I:       # %bb.0:
-; RV64I-NEXT:    lui a1, 1
-; RV64I-NEXT:    addiw a1, a1, 8
-; RV64I-NEXT:    mul a0, a0, a1
+; RV64I-NEXT:    slli a1, a0, 3
+; RV64I-NEXT:    slli a0, a0, 12
+; RV64I-NEXT:    add a0, a0, a1
 ; RV64I-NEXT:    ret
 ;
 ; RV64ZBA-LABEL: mul4104: