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[PowerPC][MC] Diagnose out of range branch fixups #165859

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[PowerPC][MC] Diagnose out of range branch fixups #165859

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24 changes: 22 additions & 2 deletions llvm/lib/Target/PowerPC/MCTargetDesc/PPCAsmBackend.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -25,7 +25,25 @@
#include "llvm/Support/ErrorHandling.h"
using namespace llvm;

static uint64_t adjustFixupValue(unsigned Kind, uint64_t Value) {
static uint64_t adjustFixupValue(MCContext &Ctx, const MCFixup &Fixup,
unsigned Kind, uint64_t Value) {
auto checkBrFixup = [&](unsigned Bits) {
int64_t SVal = int64_t(Value);
if ((Value & 3) != 0) {
Ctx.reportError(Fixup.getLoc(), "branch target not a multiple of four (" +
Twine(SVal) + ")");
return;
}

// Low two bits are not encoded.
if (!isIntN(Bits + 2, Value)) {
Ctx.reportError(Fixup.getLoc(), "branch target out of range (" +
Twine(SVal) + " not between " +
Twine(minIntN(Bits) * 4) + " and " +
Twine(maxIntN(Bits) * 4) + ")");
}
};

switch (Kind) {
default:
llvm_unreachable("Unknown fixup kind!");
Expand All @@ -37,10 +55,12 @@ static uint64_t adjustFixupValue(unsigned Kind, uint64_t Value) {
return Value;
case PPC::fixup_ppc_brcond14:
case PPC::fixup_ppc_brcond14abs:
checkBrFixup(14);
return Value & 0xfffc;
case PPC::fixup_ppc_br24:
case PPC::fixup_ppc_br24abs:
case PPC::fixup_ppc_br24_notoc:
checkBrFixup(24);
return Value & 0x3fffffc;
case PPC::fixup_ppc_half16:
return Value & 0xffff;
Expand Down Expand Up @@ -202,7 +222,7 @@ void PPCAsmBackend::applyFixup(const MCFragment &F, const MCFixup &Fixup,
MCFixupKind Kind = Fixup.getKind();
if (mc::isRelocation(Kind))
return;
Value = adjustFixupValue(Kind, Value);
Value = adjustFixupValue(getContext(), Fixup, Kind, Value);
if (!Value)
return; // Doesn't change encoding.

Expand Down
43 changes: 43 additions & 0 deletions llvm/test/MC/PowerPC/fixup-out-of-range.s
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Original file line number Diff line number Diff line change
@@ -0,0 +1,43 @@
# RUN: not llvm-mc -triple powerpc64le-unknown-unknown -filetype=obj %s 2>&1 >/dev/null | FileCheck %s

# CHECK: error: branch target out of range (32772 not between -32768 and 32764)
brcond14_out_of_range_hi:
beq 0, brcond14_target
.space 0x8000

brcond14_target:
blr

# CHECK: error: branch target out of range (-32772 not between -32768 and 32764)
brcond14_out_of_range_lo:
.space 0x8004
beq 0, brcond14_out_of_range_lo

# CHECK: error: branch target not a multiple of four (5)
brcond14_misaligned:
beq 0, brcond14_misaligned_target
.byte 0

brcond14_misaligned_target:
blr

# CHECK: error: branch target out of range (33554436 not between -33554432 and 33554428)
br24_out_of_range_hi:
b br24_target
.space 0x2000000

br24_target:
blr

# CHECK: error: branch target out of range (-33554436 not between -33554432 and 33554428)
br24_out_of_range_lo:
.space 0x2000004
b br24_out_of_range_lo

# CHECK: error: branch target not a multiple of four (5)
br24_misaligned:
b br24_misaligned_target
.byte 0

br24_misaligned_target:
blr
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