https://gcc.gnu.org/bugzilla/show_bug.cgi?id=62098
Bug ID: 62098
Summary: incorrect code generated by arm gcc
Product: gcc
Version: 4.10.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
Assignee: unassigned at gcc dot gnu.org
Reporter: carrot at google dot com
Target: arm-unknown-linux-gnueabi
Compile following source code with options -march=armv7-a -mfpu=vfpv3
-mfloat-abi=softfp -O2 -std=gnu++11
#include <limits>
#include <cmath>
const int kFixedPointDenominator = 64;
float ceilToFloat(int m_value) {
float floatValue = static_cast<float>(m_value) / kFixedPointDenominator;
if (static_cast<int>(floatValue * kFixedPointDenominator) == m_value)
return floatValue;
if (floatValue > 0)
return nextafterf(floatValue, std::numeric_limits<float>::max());
return nextafterf(floatValue, std::numeric_limits<float>::min());
}
trunk gcc generates:
fmsr s15, r0 @ int
vcvt.f32.s32 s15, s15, #6 // A
vcvt.s32.f32 s15, s15, #6 // B
vmov r3, s15
cmp r3, r0
beq .L2
fcmpezs s15
fmstat
ble .L6
movw r1, #65535
fmrs r0, s15
movt r1, 32639
b nextafterf
.L6:
mov r1, #8388608
fmrs r0, s15
b nextafterf
.L2:
fmrs r0, s15 // C
bx lr
Instruction C returns the result of instruction B, but the expected return
value is the result of instruction A.
4.9 branch generates the same wrong codes, but 4.8 is correct.
