diff options
| author | Duncan Sands <baldrick@free.fr> | 2010-11-18 20:05:18 +0000 |
|---|---|---|
| committer | Duncan Sands <baldrick@free.fr> | 2010-11-18 20:05:18 +0000 |
| commit | dcfd3a798ffbd5e02d4892eeef562c9124598844 (patch) | |
| tree | 7a9a91a019d76abf51392d3906a62b7a3ec74922 | |
| parent | d0c6f3dafd7c3e9137d4e6415014c94137fcd3fc (diff) | |
The DAGCombiner was threading select over pairs of extending loads even
if the extension types were not the same. The result was that if you
fed a select with sext and zext loads, as in the testcase, then it
would get turned into a zext (or sext) of the select, which is wrong
in the cases when it should have been an sext (resp. zext). Reported
and diagnosed by Sebastien Deldon.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@119728 91177308-0d34-0410-b5e6-96231b3b80d8
| -rw-r--r-- | lib/CodeGen/SelectionDAG/DAGCombiner.cpp | 5 | ||||
| -rw-r--r-- | test/CodeGen/X86/2010-11-18-SelectOfExtload.ll | 15 |
2 files changed, 20 insertions, 0 deletions
diff --git a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp index 1a0f503378..53b449309c 100644 --- a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp +++ b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp @@ -6658,6 +6658,11 @@ bool DAGCombiner::SimplifySelectOps(SDNode *TheSelect, SDValue LHS, LLD->isVolatile() || RLD->isVolatile() || // If this is an EXTLOAD, the VT's must match. LLD->getMemoryVT() != RLD->getMemoryVT() || + // If this is an EXTLOAD, the kind of extension must match. + (LLD->getExtensionType() != RLD->getExtensionType() && + // The only exception is if one of the extensions is anyext. + LLD->getExtensionType() != ISD::EXTLOAD && + RLD->getExtensionType() != ISD::EXTLOAD) || // FIXME: this discards src value information. This is // over-conservative. It would be beneficial to be able to remember // both potential memory locations. Since we are discarding diff --git a/test/CodeGen/X86/2010-11-18-SelectOfExtload.ll b/test/CodeGen/X86/2010-11-18-SelectOfExtload.ll new file mode 100644 index 0000000000..a1074b6b8f --- /dev/null +++ b/test/CodeGen/X86/2010-11-18-SelectOfExtload.ll @@ -0,0 +1,15 @@ +; RUN: llc < %s -march=x86 | FileCheck %s +; Both values were being zero extended. +@u = external global i8 +@s = external global i8 +define i32 @foo(i1 %cond) { +; CHECK: @foo + %u_base = load i8* @u + %u_val = zext i8 %u_base to i32 +; CHECK: movzbl +; CHECK: movsbl + %s_base = load i8* @s + %s_val = sext i8 %s_base to i32 + %val = select i1 %cond, i32 %u_val, i32 %s_val + ret i32 %val +} |