cmd/internal/obj/riscv: improve handling of invalid assembly

Currently, instruction validation failure will result in a panic during
encoding. Furthermore, the errors generated do not include the PC or
file/line information that is normally present.

Fix this by:

- Tracking and printing the *obj.Prog associated with the instruction,
  including the assembly instruction/opcode if it differs. This provides
  the standard PC and file/line prefix, which is also expected by assembly
  error end-to-end tests.

- Not proceeding with assembly if errors exist - with the current design,
  errors are identified during validation, which is run via preprocess.
  Attempts to encode invalid instructions will intentionally panic.

Add some additional riscv64 encoding errors, now that we can actually do so.

Change-Id: I64a7b83680c4d12aebdc96c67f9df625b5ef90d3
Reviewed-on: https://go-review.googlesource.com/c/go/+/523459
Run-TryBot: Joel Sing <joel@sing.id.au>
Reviewed-by: Mark Ryan <markdryan@rivosinc.com>
Reviewed-by: Heschi Kreinick <heschi@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: M Zhuo <mzh@golangcn.org>
Reviewed-by: Cherry Mui <cherryyz@google.com>
Reviewed-by: M Zhuo <mzh@golangcn.org>

diff --git a/src/cmd/asm/internal/asm/testdata/riscv64error.s b/src/cmd/asm/internal/asm/testdata/riscv64error.s
index cdb8a028bd1e93b1c329ed75678f30ca900d287b..2dc9db3fb1f6be9542a7a52c583fe9e18a593501 100644 (file)
--- a/src/cmd/asm/internal/asm/testdata/riscv64error.s
+++ b/src/cmd/asm/internal/asm/testdata/riscv64error.s
@@ -38,5 +38,8 @@ TEXT errors(SB),$0
        SLLIW   $-1, X5, X6                     // ERROR "shift amount out of range 0 to 31"
        SRLIW   $-1, X5, X6                     // ERROR "shift amount out of range 0 to 31"
        SRAIW   $-1, X5, X6                     // ERROR "shift amount out of range 0 to 31"
-
+       SD      X5, 4294967296(X6)              // ERROR "constant 4294967296 too large"
+       SRLI    $1, X5, F1                      // ERROR "expected integer register in rd position but got non-integer register F1"
+       SRLI    $1, F1, X5                      // ERROR "expected integer register in rs1 position but got non-integer register F1"
+       FNES    F1, (X5)                        // ERROR "needs an integer register output"
        RET

diff --git a/src/cmd/internal/obj/riscv/obj.go b/src/cmd/internal/obj/riscv/obj.go
index 4ff1d910ce3aa8f1c514173b3d33130efd183721..93bda45096148934a689cf0dfb09416f279512de 100644 (file)
--- a/src/cmd/internal/obj/riscv/obj.go
+++ b/src/cmd/internal/obj/riscv/obj.go
@@ -1043,154 +1043,154 @@ func immI(as obj.As, imm int64, nbits uint) uint32 {
        return uint32(imm)
 }
 
-func wantImmI(ctxt *obj.Link, as obj.As, imm int64, nbits uint) {
+func wantImmI(ctxt *obj.Link, ins *instruction, imm int64, nbits uint) {
        if err := immIFits(imm, nbits); err != nil {
-               ctxt.Diag("%v: %v", as, err)
+               ctxt.Diag("%v: %v", ins, err)
        }
 }
 
-func wantReg(ctxt *obj.Link, as obj.As, pos string, descr string, r, min, max uint32) {
+func wantReg(ctxt *obj.Link, ins *instruction, pos string, descr string, r, min, max uint32) {
        if r < min || r > max {
                var suffix string
                if r != obj.REG_NONE {
                        suffix = fmt.Sprintf(" but got non-%s register %s", descr, RegName(int(r)))
                }
-               ctxt.Diag("%v: expected %s register in %s position%s", as, descr, pos, suffix)
+               ctxt.Diag("%v: expected %s register in %s position%s", ins, descr, pos, suffix)
        }
 }
 
-func wantNoneReg(ctxt *obj.Link, as obj.As, pos string, r uint32) {
+func wantNoneReg(ctxt *obj.Link, ins *instruction, pos string, r uint32) {
        if r != obj.REG_NONE {
-               ctxt.Diag("%v: expected no register in %s but got register %s", as, pos, RegName(int(r)))
+               ctxt.Diag("%v: expected no register in %s but got register %s", ins, pos, RegName(int(r)))
        }
 }
 
 // wantIntReg checks that r is an integer register.
-func wantIntReg(ctxt *obj.Link, as obj.As, pos string, r uint32) {
-       wantReg(ctxt, as, pos, "integer", r, REG_X0, REG_X31)
+func wantIntReg(ctxt *obj.Link, ins *instruction, pos string, r uint32) {
+       wantReg(ctxt, ins, pos, "integer", r, REG_X0, REG_X31)
 }
 
 // wantFloatReg checks that r is a floating-point register.
-func wantFloatReg(ctxt *obj.Link, as obj.As, pos string, r uint32) {
-       wantReg(ctxt, as, pos, "float", r, REG_F0, REG_F31)
+func wantFloatReg(ctxt *obj.Link, ins *instruction, pos string, r uint32) {
+       wantReg(ctxt, ins, pos, "float", r, REG_F0, REG_F31)
 }
 
 // wantEvenOffset checks that the offset is a multiple of two.
-func wantEvenOffset(ctxt *obj.Link, as obj.As, offset int64) {
+func wantEvenOffset(ctxt *obj.Link, ins *instruction, offset int64) {
        if err := immEven(offset); err != nil {
-               ctxt.Diag("%v: %v", as, err)
+               ctxt.Diag("%v: %v", ins, err)
        }
 }
 
 func validateRIII(ctxt *obj.Link, ins *instruction) {
-       wantIntReg(ctxt, ins.as, "rd", ins.rd)
-       wantIntReg(ctxt, ins.as, "rs1", ins.rs1)
-       wantIntReg(ctxt, ins.as, "rs2", ins.rs2)
-       wantNoneReg(ctxt, ins.as, "rs3", ins.rs3)
+       wantIntReg(ctxt, ins, "rd", ins.rd)
+       wantIntReg(ctxt, ins, "rs1", ins.rs1)
+       wantIntReg(ctxt, ins, "rs2", ins.rs2)
+       wantNoneReg(ctxt, ins, "rs3", ins.rs3)
 }
 
 func validateRFFF(ctxt *obj.Link, ins *instruction) {
-       wantFloatReg(ctxt, ins.as, "rd", ins.rd)
-       wantFloatReg(ctxt, ins.as, "rs1", ins.rs1)
-       wantFloatReg(ctxt, ins.as, "rs2", ins.rs2)
-       wantNoneReg(ctxt, ins.as, "rs3", ins.rs3)
+       wantFloatReg(ctxt, ins, "rd", ins.rd)
+       wantFloatReg(ctxt, ins, "rs1", ins.rs1)
+       wantFloatReg(ctxt, ins, "rs2", ins.rs2)
+       wantNoneReg(ctxt, ins, "rs3", ins.rs3)
 }
 
 func validateRFFFF(ctxt *obj.Link, ins *instruction) {
-       wantFloatReg(ctxt, ins.as, "rd", ins.rd)
-       wantFloatReg(ctxt, ins.as, "rs1", ins.rs1)
-       wantFloatReg(ctxt, ins.as, "rs2", ins.rs2)
-       wantFloatReg(ctxt, ins.as, "rs3", ins.rs3)
+       wantFloatReg(ctxt, ins, "rd", ins.rd)
+       wantFloatReg(ctxt, ins, "rs1", ins.rs1)
+       wantFloatReg(ctxt, ins, "rs2", ins.rs2)
+       wantFloatReg(ctxt, ins, "rs3", ins.rs3)
 }
 
 func validateRFFI(ctxt *obj.Link, ins *instruction) {
-       wantIntReg(ctxt, ins.as, "rd", ins.rd)
-       wantFloatReg(ctxt, ins.as, "rs1", ins.rs1)
-       wantFloatReg(ctxt, ins.as, "rs2", ins.rs2)
-       wantNoneReg(ctxt, ins.as, "rs3", ins.rs3)
+       wantIntReg(ctxt, ins, "rd", ins.rd)
+       wantFloatReg(ctxt, ins, "rs1", ins.rs1)
+       wantFloatReg(ctxt, ins, "rs2", ins.rs2)
+       wantNoneReg(ctxt, ins, "rs3", ins.rs3)
 }
 
 func validateRFI(ctxt *obj.Link, ins *instruction) {
-       wantIntReg(ctxt, ins.as, "rd", ins.rd)
-       wantNoneReg(ctxt, ins.as, "rs1", ins.rs1)
-       wantFloatReg(ctxt, ins.as, "rs2", ins.rs2)
-       wantNoneReg(ctxt, ins.as, "rs3", ins.rs3)
+       wantIntReg(ctxt, ins, "rd", ins.rd)
+       wantNoneReg(ctxt, ins, "rs1", ins.rs1)
+       wantFloatReg(ctxt, ins, "rs2", ins.rs2)
+       wantNoneReg(ctxt, ins, "rs3", ins.rs3)
 }
 
 func validateRIF(ctxt *obj.Link, ins *instruction) {
-       wantFloatReg(ctxt, ins.as, "rd", ins.rd)
-       wantNoneReg(ctxt, ins.as, "rs1", ins.rs1)
-       wantIntReg(ctxt, ins.as, "rs2", ins.rs2)
-       wantNoneReg(ctxt, ins.as, "rs3", ins.rs3)
+       wantFloatReg(ctxt, ins, "rd", ins.rd)
+       wantNoneReg(ctxt, ins, "rs1", ins.rs1)
+       wantIntReg(ctxt, ins, "rs2", ins.rs2)
+       wantNoneReg(ctxt, ins, "rs3", ins.rs3)
 }
 
 func validateRFF(ctxt *obj.Link, ins *instruction) {
-       wantFloatReg(ctxt, ins.as, "rd", ins.rd)
-       wantNoneReg(ctxt, ins.as, "rs1", ins.rs1)
-       wantFloatReg(ctxt, ins.as, "rs2", ins.rs2)
-       wantNoneReg(ctxt, ins.as, "rs3", ins.rs3)
+       wantFloatReg(ctxt, ins, "rd", ins.rd)
+       wantNoneReg(ctxt, ins, "rs1", ins.rs1)
+       wantFloatReg(ctxt, ins, "rs2", ins.rs2)
+       wantNoneReg(ctxt, ins, "rs3", ins.rs3)
 }
 
 func validateII(ctxt *obj.Link, ins *instruction) {
-       wantImmI(ctxt, ins.as, ins.imm, 12)
-       wantIntReg(ctxt, ins.as, "rd", ins.rd)
-       wantIntReg(ctxt, ins.as, "rs1", ins.rs1)
-       wantNoneReg(ctxt, ins.as, "rs2", ins.rs2)
-       wantNoneReg(ctxt, ins.as, "rs3", ins.rs3)
+       wantImmI(ctxt, ins, ins.imm, 12)
+       wantIntReg(ctxt, ins, "rd", ins.rd)
+       wantIntReg(ctxt, ins, "rs1", ins.rs1)
+       wantNoneReg(ctxt, ins, "rs2", ins.rs2)
+       wantNoneReg(ctxt, ins, "rs3", ins.rs3)
 }
 
 func validateIF(ctxt *obj.Link, ins *instruction) {
-       wantImmI(ctxt, ins.as, ins.imm, 12)
-       wantFloatReg(ctxt, ins.as, "rd", ins.rd)
-       wantIntReg(ctxt, ins.as, "rs1", ins.rs1)
-       wantNoneReg(ctxt, ins.as, "rs2", ins.rs2)
-       wantNoneReg(ctxt, ins.as, "rs3", ins.rs3)
+       wantImmI(ctxt, ins, ins.imm, 12)
+       wantFloatReg(ctxt, ins, "rd", ins.rd)
+       wantIntReg(ctxt, ins, "rs1", ins.rs1)
+       wantNoneReg(ctxt, ins, "rs2", ins.rs2)
+       wantNoneReg(ctxt, ins, "rs3", ins.rs3)
 }
 
 func validateSI(ctxt *obj.Link, ins *instruction) {
-       wantImmI(ctxt, ins.as, ins.imm, 12)
-       wantIntReg(ctxt, ins.as, "rd", ins.rd)
-       wantIntReg(ctxt, ins.as, "rs1", ins.rs1)
-       wantNoneReg(ctxt, ins.as, "rs2", ins.rs2)
-       wantNoneReg(ctxt, ins.as, "rs3", ins.rs3)
+       wantImmI(ctxt, ins, ins.imm, 12)
+       wantIntReg(ctxt, ins, "rd", ins.rd)
+       wantIntReg(ctxt, ins, "rs1", ins.rs1)
+       wantNoneReg(ctxt, ins, "rs2", ins.rs2)
+       wantNoneReg(ctxt, ins, "rs3", ins.rs3)
 }
 
 func validateSF(ctxt *obj.Link, ins *instruction) {
-       wantImmI(ctxt, ins.as, ins.imm, 12)
-       wantIntReg(ctxt, ins.as, "rd", ins.rd)
-       wantFloatReg(ctxt, ins.as, "rs1", ins.rs1)
-       wantNoneReg(ctxt, ins.as, "rs2", ins.rs2)
-       wantNoneReg(ctxt, ins.as, "rs3", ins.rs3)
+       wantImmI(ctxt, ins, ins.imm, 12)
+       wantIntReg(ctxt, ins, "rd", ins.rd)
+       wantFloatReg(ctxt, ins, "rs1", ins.rs1)
+       wantNoneReg(ctxt, ins, "rs2", ins.rs2)
+       wantNoneReg(ctxt, ins, "rs3", ins.rs3)
 }
 
 func validateB(ctxt *obj.Link, ins *instruction) {
        // Offsets are multiples of two, so accept 13 bit immediates for the
        // 12 bit slot. We implicitly drop the least significant bit in encodeB.
-       wantEvenOffset(ctxt, ins.as, ins.imm)
-       wantImmI(ctxt, ins.as, ins.imm, 13)
-       wantNoneReg(ctxt, ins.as, "rd", ins.rd)
-       wantIntReg(ctxt, ins.as, "rs1", ins.rs1)
-       wantIntReg(ctxt, ins.as, "rs2", ins.rs2)
-       wantNoneReg(ctxt, ins.as, "rs3", ins.rs3)
+       wantEvenOffset(ctxt, ins, ins.imm)
+       wantImmI(ctxt, ins, ins.imm, 13)
+       wantNoneReg(ctxt, ins, "rd", ins.rd)
+       wantIntReg(ctxt, ins, "rs1", ins.rs1)
+       wantIntReg(ctxt, ins, "rs2", ins.rs2)
+       wantNoneReg(ctxt, ins, "rs3", ins.rs3)
 }
 
 func validateU(ctxt *obj.Link, ins *instruction) {
-       wantImmI(ctxt, ins.as, ins.imm, 20)
-       wantIntReg(ctxt, ins.as, "rd", ins.rd)
-       wantNoneReg(ctxt, ins.as, "rs1", ins.rs1)
-       wantNoneReg(ctxt, ins.as, "rs2", ins.rs2)
-       wantNoneReg(ctxt, ins.as, "rs3", ins.rs3)
+       wantImmI(ctxt, ins, ins.imm, 20)
+       wantIntReg(ctxt, ins, "rd", ins.rd)
+       wantNoneReg(ctxt, ins, "rs1", ins.rs1)
+       wantNoneReg(ctxt, ins, "rs2", ins.rs2)
+       wantNoneReg(ctxt, ins, "rs3", ins.rs3)
 }
 
 func validateJ(ctxt *obj.Link, ins *instruction) {
        // Offsets are multiples of two, so accept 21 bit immediates for the
        // 20 bit slot. We implicitly drop the least significant bit in encodeJ.
-       wantEvenOffset(ctxt, ins.as, ins.imm)
-       wantImmI(ctxt, ins.as, ins.imm, 21)
-       wantIntReg(ctxt, ins.as, "rd", ins.rd)
-       wantNoneReg(ctxt, ins.as, "rs1", ins.rs1)
-       wantNoneReg(ctxt, ins.as, "rs2", ins.rs2)
-       wantNoneReg(ctxt, ins.as, "rs3", ins.rs3)
+       wantEvenOffset(ctxt, ins, ins.imm)
+       wantImmI(ctxt, ins, ins.imm, 21)
+       wantIntReg(ctxt, ins, "rd", ins.rd)
+       wantNoneReg(ctxt, ins, "rs1", ins.rs1)
+       wantNoneReg(ctxt, ins, "rs2", ins.rs2)
+       wantNoneReg(ctxt, ins, "rs3", ins.rs3)
 }
 
 func validateRaw(ctxt *obj.Link, ins *instruction) {
@@ -1727,14 +1727,26 @@ func encodingForAs(as obj.As) (encoding, error) {
 }
 
 type instruction struct {
-       as     obj.As // Assembler opcode
-       rd     uint32 // Destination register
-       rs1    uint32 // Source register 1
-       rs2    uint32 // Source register 2
-       rs3    uint32 // Source register 3
-       imm    int64  // Immediate
-       funct3 uint32 // Function 3
-       funct7 uint32 // Function 7 (or Function 2)
+       p      *obj.Prog // Prog that instruction is for
+       as     obj.As    // Assembler opcode
+       rd     uint32    // Destination register
+       rs1    uint32    // Source register 1
+       rs2    uint32    // Source register 2
+       rs3    uint32    // Source register 3
+       imm    int64     // Immediate
+       funct3 uint32    // Function 3
+       funct7 uint32    // Function 7 (or Function 2)
+}
+
+func (ins *instruction) String() string {
+       if ins.p == nil {
+               return ins.as.String()
+       }
+       var suffix string
+       if ins.p.As != ins.as {
+               suffix = fmt.Sprintf(" (%v)", ins.as)
+       }
+       return fmt.Sprintf("%v%v", ins.p, suffix)
 }
 
 func (ins *instruction) encode() (uint32, error) {
@@ -2200,13 +2212,13 @@ func instructionsForProg(p *obj.Prog) []*instruction {
                ins.imm = p.To.Offset
 
        case AMOV, AMOVB, AMOVH, AMOVW, AMOVBU, AMOVHU, AMOVWU, AMOVF, AMOVD:
-               return instructionsForMOV(p)
+               inss = instructionsForMOV(p)
 
        case ALW, ALWU, ALH, ALHU, ALB, ALBU, ALD, AFLW, AFLD:
-               return instructionsForLoad(p, ins.as, p.From.Reg)
+               inss = instructionsForLoad(p, ins.as, p.From.Reg)
 
        case ASW, ASH, ASB, ASD, AFSW, AFSD:
-               return instructionsForStore(p, ins.as, p.To.Reg)
+               inss = instructionsForStore(p, ins.as, p.To.Reg)
 
        case ALRW, ALRD:
                // Set aq to use acquire access ordering
@@ -2246,7 +2258,7 @@ func instructionsForProg(p *obj.Prog) []*instruction {
        case AFNES, AFNED:
                // Replace FNE[SD] with FEQ[SD] and NOT.
                if p.To.Type != obj.TYPE_REG {
-                       p.Ctxt.Diag("%v needs an integer register output", ins.as)
+                       p.Ctxt.Diag("%v needs an integer register output", p)
                        return nil
                }
                if ins.as == AFNES {
@@ -2335,6 +2347,11 @@ func instructionsForProg(p *obj.Prog) []*instruction {
                        p.Ctxt.Diag("%v: shift amount out of range 0 to 31", p)
                }
        }
+
+       for _, ins := range inss {
+               ins.p = p
+       }
+
        return inss
 }
 
@@ -2346,6 +2363,12 @@ func assemble(ctxt *obj.Link, cursym *obj.LSym, newprog obj.ProgAlloc) {
                ctxt.Retpoline = false // don't keep printing
        }
 
+       // If errors were encountered during preprocess/validation, proceeding
+       // and attempting to encode said instructions will only lead to panics.
+       if ctxt.Errors > 0 {
+               return
+       }
+
        for p := cursym.Func().Text; p != nil; p = p.Link {
                switch p.As {
                case AJAL: