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| author | Benjamin Kramer <benny.kra@googlemail.com> | 2013-07-06 14:05:09 +0000 |
|---|---|---|
| committer | Benjamin Kramer <benny.kra@googlemail.com> | 2013-07-06 14:05:09 +0000 |
| commit | f4eeab452ad4093986359c78a57321df12df99b0 (patch) | |
| tree | 18e20c9044ed731be0e644bf0d52fe54f4155ad1 /test | |
| parent | e5a81a130f26b0b2651ad6a22e3748703b11cb46 (diff) | |
| download | llvm-f4eeab452ad4093986359c78a57321df12df99b0.tar.gz llvm-f4eeab452ad4093986359c78a57321df12df99b0.tar.bz2 llvm-f4eeab452ad4093986359c78a57321df12df99b0.tar.xz | |
DAGCombiner: Don't drop extension behavior when shrinking a load when unsafe.
ReduceLoadWidth unconditionally drops extensions from loads. Limit it to the
case when all of the bits the extension would otherwise produce are dropped by
the shrink. It would be possible to shrink the load in more cases by merging
the extensions, but this isn't trivial and a very rare case. I left a TODO for
that case.
Fixes PR16551.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@185755 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'test')
| -rw-r--r-- | test/CodeGen/X86/shrink-compare.ll | 23 |
1 files changed, 23 insertions, 0 deletions
diff --git a/test/CodeGen/X86/shrink-compare.ll b/test/CodeGen/X86/shrink-compare.ll index 83793f000d..30a5b6207d 100644 --- a/test/CodeGen/X86/shrink-compare.ll +++ b/test/CodeGen/X86/shrink-compare.ll @@ -66,3 +66,26 @@ lor.end: ; preds = %lor.rhs, %entry %p = phi i1 [ true, %entry ], [ %tobool1, %lor.rhs ] ret i1 %p } + +@x = global { i8, i8, i8, i8, i8, i8, i8, i8 } { i8 1, i8 0, i8 0, i8 0, i8 1, i8 0, i8 0, i8 1 }, align 4 + +; PR16551 +define void @test5(i32 %X) nounwind { +entry: + %bf.load = load i56* bitcast ({ i8, i8, i8, i8, i8, i8, i8, i8 }* @x to i56*), align 4 + %bf.lshr = lshr i56 %bf.load, 32 + %bf.cast = trunc i56 %bf.lshr to i32 + %cmp = icmp ne i32 %bf.cast, 1 + br i1 %cmp, label %if.then, label %if.end + +if.then: + tail call void @bar() nounwind + br label %if.end + +if.end: + ret void + +; CHECK: test5: +; CHECK-NOT: cmpl $1,{{.*}}x+4 +; CHECK: ret +} |