diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/cmd/asm/internal/asm/testdata/riscv64.s | 4 | ||||
| -rw-r--r-- | src/cmd/internal/obj/riscv/obj.go | 32 |
2 files changed, 34 insertions, 2 deletions
diff --git a/src/cmd/asm/internal/asm/testdata/riscv64.s b/src/cmd/asm/internal/asm/testdata/riscv64.s index 79d6054869..6f303858b4 100644 --- a/src/cmd/asm/internal/asm/testdata/riscv64.s +++ b/src/cmd/asm/internal/asm/testdata/riscv64.s @@ -318,7 +318,9 @@ start: MOV $-2147483647, X5 // b70200809b821200 // Converted to load of symbol (AUIPC + LD) - MOV $4294967296, X5 // 9702000083b20200 + MOV $4294967295, X5 // 9702000083b20200 + // Converted to MOV $1, X5 + SLLI $32, X5 + MOV $4294967296, X5 // 9302100093920202 MOV (X5), X6 // 03b30200 MOV 4(X5), X6 // 03b34200 diff --git a/src/cmd/internal/obj/riscv/obj.go b/src/cmd/internal/obj/riscv/obj.go index cbf894817d..8aa76a670d 100644 --- a/src/cmd/internal/obj/riscv/obj.go +++ b/src/cmd/internal/obj/riscv/obj.go @@ -26,6 +26,7 @@ import ( "cmd/internal/sys" "fmt" "log" + "math/bits" ) func buildop(ctxt *obj.Link) {} @@ -140,8 +141,14 @@ func progedit(ctxt *obj.Link, p *obj.Prog, newprog obj.ProgAlloc) { p.As = AEBREAK case AMOV: - // Put >32-bit constants in memory and load them. if p.From.Type == obj.TYPE_CONST && p.From.Name == obj.NAME_NONE && p.From.Reg == obj.REG_NONE && int64(int32(p.From.Offset)) != p.From.Offset { + ctz := bits.TrailingZeros64(uint64(p.From.Offset)) + val := p.From.Offset >> ctz + if int64(int32(val)) == val { + // It's ok. We can handle constants with many trailing zeros. + break + } + // Put >32-bit constants in memory and load them. p.From.Type = obj.TYPE_MEM p.From.Sym = ctxt.Int64Sym(p.From.Offset) p.From.Name = obj.NAME_EXTERN @@ -1838,6 +1845,23 @@ func instructionsForMOV(p *obj.Prog) []*instruction { return nil } + // For constants larger than 32 bits in size that have trailing zeros, + // use the value with the trailing zeros removed and then use a SLLI + // instruction to restore the original constant. + // For example: + // MOV $0x8000000000000000, X10 + // becomes + // MOV $1, X10 + // SLLI $63, X10, X10 + var insSLLI *instruction + if !immIFits(ins.imm, 32) { + ctz := bits.TrailingZeros64(uint64(ins.imm)) + if immIFits(ins.imm>>ctz, 32) { + ins.imm = ins.imm >> ctz + insSLLI = &instruction{as: ASLLI, rd: ins.rd, rs1: ins.rd, imm: int64(ctz)} + } + } + low, high, err := Split32BitImmediate(ins.imm) if err != nil { p.Ctxt.Diag("%v: constant %d too large: %v", p, ins.imm, err) @@ -1849,6 +1873,9 @@ func instructionsForMOV(p *obj.Prog) []*instruction { // LUI is only necessary if the constant does not fit in 12 bits. if high == 0 { + if insSLLI != nil { + inss = append(inss, insSLLI) + } break } @@ -1860,6 +1887,9 @@ func instructionsForMOV(p *obj.Prog) []*instruction { ins.as, ins.rs1 = AADDIW, ins.rd inss = append(inss, ins) } + if insSLLI != nil { + inss = append(inss, insSLLI) + } case p.From.Type == obj.TYPE_CONST && p.To.Type != obj.TYPE_REG: p.Ctxt.Diag("%v: constant load must target register", p) |