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llvm-mirror/test/CodeGen/SystemZ/int-cmp-53.ll
Ulrich Weigand c791b42454 [SystemZ] Fix wrong-code generation for certain always-false conditions
We've found another bug in the code generation logic conditions for a
certain class of always-false conditions, those of the form
   if ((a & 1) < 0)

These only reach the back end when compiling without optimization.

The bug was introduced by the choice of using TEST UNDER MASK
to implement a check for
   if ((a & MASK) < VAL)
as
   if ((a & MASK) == 0)

where VAL is less than the the lowest bit of MASK.  This is correct
in all cases except for VAL == 0, in which case the original
condition is always false, but the replacement isn't.

Fixed by excluding that particular case.

llvm-svn: 259381
2016-02-01 18:31:19 +00:00

27 lines
516 B
LLVM

; This used to incorrectly use a TMLL for an always-false test at -O0.
;
; RUN: llc -O0 < %s -mtriple=s390x-linux-gnu | FileCheck %s
define void @test(i8 *%input, i32 *%result) {
entry:
; CHECK-NOT: tmll
%0 = load i8, i8* %input, align 1
%1 = trunc i8 %0 to i1
%2 = zext i1 %1 to i32
%3 = icmp sge i32 %2, 0
br i1 %3, label %if.then, label %if.else
if.then:
store i32 1, i32* %result, align 4
br label %return
if.else:
store i32 0, i32* %result, align 4
br label %return
return:
ret void
}