error: illegal "f" output constraint; fatal error: error in backend: Access past stack top! (also: Cannot pop empty stack!)

[llvmbot]

Bugzilla Link	14642
Version	trunk
OS	FreeBSD
Attachments	preprocessed source (boring...), run script (boring...)
Reporter	LLVM Bugzilla Contributor
CC	@rengolin

Extended Description

1. source code (file name: f.c):

void f(void)
{
	float x;
	__asm__ (
		""
		: "=f" (x)
	);
}

2. command line:

clang -c f.c

3. output:

f.c:5:3: error: illegal "f" output constraint
                ""
                ^
fatal error: error in backend: Access past stack top!
clang: error: clang frontend command failed with exit code 70 (use -v to see invocation)
clang version 3.3 (trunk 170425)
Target: i386-unknown-freebsd10.0
Thread model: posix

[llvmbot]

0. similar test case, yields:

fatal error: error in backend: Cannot pop empty stack!

1. source code (file name: f.c):

void f(void)
{
	float x;
	__asm__ (
		""
		: "=f" (x)
		: "f" (x)
	);
}

2. command line:

clang -c f.c

3. output:

f.c:5:3: error: illegal "f" output constraint
                ""
                ^
fatal error: error in backend: Cannot pop empty stack!
clang: error: clang frontend command failed with exit code 70 (use -v to see invocation)
clang version 3.3 (trunk 170425)
Target: i386-unknown-freebsd10.0
Thread model: posix

[llvmbot]

run script (boring...)

[llvmbot]

preprocessed source (boring...)

[llvmbot]

mentioned in issue llvm/llvm-bugzilla-archive#26521

[llvmbot]

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