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https://github.com/c64scene-ar/llvm-6502.git
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7a2bdde0a0
Luis Felipe Strano Moraes! git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@129558 91177308-0d34-0410-b5e6-96231b3b80d8
19 lines
773 B
C
19 lines
773 B
C
// RUN: %llvmgcc -S %s -o - | FileCheck %s
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extern int printf(const char *, ...);
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static void bad(unsigned int v1, unsigned int v2) {
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printf("%u\n", 1631381461u * (((v2 - 1273463329u <= v1 - 1273463329u) ? v2 : v1) - 1273463329u) + 121322179u);
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}
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// Radar 8198362
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// GCC FE wants to convert the above to
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// 1631381461u * MIN(v2 - 1273463329u, v1 - 1273463329u)
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// and then to
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// MIN(1631381461u * v2 - 4047041419, 1631381461u * v1 - 4047041419)
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//
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// 1631381461u * 1273463329u = 2077504466193943669, but 32-bit overflow clips
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// this to 4047041419. This breaks the comparison implicit in the MIN().
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// Two multiply operations suggests the bad optimization is happening;
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// one multiplication, after the MIN(), is correct.
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// CHECK: mul
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// CHECK-NOT: mul
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// CHECK: ret
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