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Type:
Bug
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Resolution: Fixed
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Priority:
Medium
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Code Generation Tools
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CODEGEN-12673
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default
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Use --opt_level=off or avoid using volatile variables in the compare.
The C28 Compiler's saturation optimization for if/ternary max check generates incorrect results for volatile variable values above a constant max limit.
The issue occurs with:
--float_support=fpu64
--opt_level=0-4
volatile compares involving doubles and floating point constants
volatile variable's value is greater than a constant max limit
Example C code::
volatile double x_volatile;
if(x_volatile > 4) x_volatile=4;
x_volatile = (x_volatile > 4) ? 4 : x_volatile;
In the generated assembly, the GEQ condition code should instead be LT:
MOV32 *-SP[4],R0L
MOV32 *-SP[2],R0H
MOV32 R0H,*-SP[2]
MOV32 R0L,*-SP[4]
MINF64 R0,#16400
NOP ; [CPU_ALU]
MOV32 R0H,*-SP[2],GEQ <-- Should be LT
MOV32 R0L,*-SP[4],GEQ <-- Should be LT
MOV32 *-SP[4],R0L
MOV32 *-SP[2],R0H
MOV32 R0H,*-SP[2]
MOV32 R0L,*-SP[4]
