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954ec09aed
Syntax:
asm [volatile] goto ( AssemblerTemplate
:
: InputOperands
: Clobbers
: GotoLabels)
https://gcc.gnu.org/onlinedocs/gcc/Extended-Asm.html
New llvm IR is "callbr" for inline asm goto instead "call" for inline asm
For:
asm goto("testl %0, %0; jne %l1;" :: "r"(cond)::label_true, loop);
IR:
callbr void asm sideeffect "testl $0, $0; jne ${1:l};", "r,X,X,~{dirflag},~{fpsr},~{flags}"(i32 %0, i8* blockaddress(@foo, %label_true), i8* blockaddress(@foo, %loop)) #1
to label %asm.fallthrough [label %label_true, label %loop], !srcloc !3
asm.fallthrough:
Compiler need to generate:
1> a dummy constarint 'X' for each label.
2> an unique fallthrough label for each asm goto stmt " asm.fallthrough%number".
Diagnostic
1> duplicate asm operand name are used in output, input and label.
2> goto out of scope.
llvm-svn: 362045
19 lines
413 B
C
19 lines
413 B
C
// Header for the PCH test asm.c
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void f() {
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int i,cond;
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asm ("foo\n" : : "a" (i + 2));
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asm ("foo\n" : [symbolic_name] "=a" (i) : "[symbolic_name]" (i));
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asm volatile goto("testl %0, %0; jne %l1;" :: "r"(cond)::label_true, loop);
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label_true:
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loop:
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return;
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}
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void clobbers() {
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asm ("nop" : : : "ax", "#ax", "%ax");
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asm ("nop" : : : "eax", "rax", "ah", "al");
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asm ("nop" : : : "0", "%0", "#0");
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}
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