[LLVMbugs] [Bug 20472] New: Regression of llc between LLVM revisions 213897 and 213898.

[bugzilla-daemon at llvm.org]

http://llvm.org/bugs/show_bug.cgi?id=20472

            Bug ID: 20472
           Summary: Regression of llc between LLVM revisions 213897 and
                    213898.
           Product: tools
           Version: trunk
          Hardware: PC
                OS: Linux
            Status: NEW
          Severity: normal
          Priority: P
         Component: llc
          Assignee: unassignedbugs at nondot.org
          Reporter: anton.mitrokhin at phystech.edu
                CC: llvmbugs at cs.uiuc.edu
    Classification: Unclassified

Reproducer:
a.ll:
target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-unknown-linux-gnu"

; Function Attrs: nounwind
define void @f_fu(float* noalias nocapture %RET) #1 {
allocas:

  %resultvec.i67 = select <8 x i1> <i1 1, i1 0, i1 0, i1 1, i1 1, i1 1, i1 1,
i1 0>, <8 x i16> <i16 128, i16 128, i16 128, i16 128, i16 128, i16 128, i16
128, i16 128>, <8 x i16> <i16 -500, i16 -500, i16 -500, i16 -500, i16 -500, i16
-500, i16 -500, i16 -500>

  %result_load15_to_int8.i = trunc <8 x i16> %resultvec.i67 to <8 x i8>
  %calltmp_to_float = sitofp <8 x i8> %result_load15_to_int8.i to <8 x float>
  %ptrcast = bitcast float* %RET to <8 x float>*
  store <8 x float> %calltmp_to_float, <8 x float>* %ptrcast, align 4

  ret void
}


test_static.cpp:
#include <stdio.h>
extern "C" {
    extern void f_fu(float *result);
}

int main(int argc, char *argv[]) {
    float returned_result[4];
    f_fu(returned_result);


    printf("\n");
    printf("res[0] = %f\n", returned_result[0]);
    printf("res[1] = %f\n", returned_result[1]);

    return 0;
}


Building:

.../llvm/bin-trunk_r213897/bin/llc a.ll -o old.s --mattr='+sse4.1'
clang++ test_static.cpp old.s -o bin_old

.../llvm/bin-trunk_r213898/bin/llc a.ll -o new.s --mattr='+sse4.1'
clang++ test_static.cpp new.s -o bin_new

right:
./bin_old
res[0] = -128.000000
res[1] = 12.000000

wrong:
./bin_new
res[0] = 128.000000
res[1] = -500.000000

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