IT-block ends prematurely

Technical Note 31138

Targets:
ARM

Component:
Compiler

Updated:
2/25/2015 8:25 AM

Introduction

IAR Embedded Workbench for ARM version 7.30 (and earlier) accepted constructions like:

[...]
asm("ITE EQ");
asm("MRSEQ R0, MSP");
asm("MRSNE R0, PSP");
[...]

The above is a bug which is corrected in IAR Embedded Workbench for ARM version 7.40.1.

The code above will generate diagnostic messages like:

Error[Ta117]: IT-block ends prematurely, or there is a label within the IT-block

Discussion

The construction above is unsafe, as in-between the asm()-statements it was possible to place ordinary C source code.

Suggested rewrite

Change the construction into a single inline assebler statement, with multiple lines.

The above construction should be rewritten to:

[...]
asm("ITE EQ \n"
"MRSEQ R0, MSP \n"
"MRSNE R0, PSP");
[...]

 

 

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