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ARM: Link register is trashed by non-executed branch and link operations.

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This commit is contained in:
Jack Whitman 2009-06-24 21:22:46 -07:00
parent 6dd4272804
commit 853a0858f3
2 changed files with 10 additions and 2 deletions
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4
src/arch/arm/isa/decoder.isa
View file

@ -246,7 +246,7 @@ decode COND_CODE default Unknown::unknown() {
}});
}
0x3: decode OPCODE_24_21 {
0x9: BranchExchange::blx({{ LR = NPC; }});
0x9: BranchExchange::blx({{ }}, Link);
}
}
}
@ -661,7 +661,7 @@ decode COND_CODE default Unknown::unknown() {
0x5: decode OPCODE_24 {
// Branch (and Link) Instructions
0: Branch::b({{ }});
1: Branch::bl({{ LR = NPC; }});
1: Branch::bl({{ }}, Link);
}
0x6: decode CPNUM {
0x1: decode PUNWL {

8
src/arch/arm/isa/formats/branch.isa
View file

@ -38,8 +38,10 @@ def format Branch(code,*opt_flags) {{
#Build Instruction Flags
#Use Link & Likely Flags to Add Link/Condition Code
inst_flags = ('IsDirectControl', )
linking = False
for x in opt_flags:
if x == 'Link':
linking = True
code += 'LR = NPC;\n'
else:
inst_flags += (x, )
@ -55,6 +57,8 @@ def format Branch(code,*opt_flags) {{
icode += ' NPC = NPC + 4 + disp;\n'
icode += '} else {\n'
icode += ' NPC = NPC;\n'
if linking:
icode += ' LR = LR;\n'
icode += '};\n'
code = icode
@ -70,8 +74,10 @@ def format BranchExchange(code,*opt_flags) {{
#Build Instruction Flags
#Use Link & Likely Flags to Add Link/Condition Code
inst_flags = ('IsIndirectControl', )
linking = False
for x in opt_flags:
if x == 'Link':
linking = True
code += 'LR = NPC;\n'
else:
inst_flags += (x, )
@ -89,6 +95,8 @@ def format BranchExchange(code,*opt_flags) {{
icode += ' NPC = Rm & 0xfffffffe; // Masks off bottom bit\n'
icode += '} else {\n'
icode += ' NPC = NPC;\n'
if linking:
icode += ' LR = LR;\n'
icode += '};\n'
code = icode