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| author | Nick Lewycky <nicholas@mxc.ca> | 2011-01-22 22:06:21 +0000 |
|---|---|---|
| committer | Nick Lewycky <nicholas@mxc.ca> | 2011-01-22 22:06:21 +0000 |
| commit | b32c8943e6e03806f81a6e3d7b5a228c89fe746c (patch) | |
| tree | c78b6da2c20b70603ef16afe57b1fc78476311b8 /llvm/lib/Analysis | |
| parent | c70e037b73f21cd638031b2e32c1c8720c684916 (diff) | |
| download | bcm5719-llvm-b32c8943e6e03806f81a6e3d7b5a228c89fe746c.tar.gz bcm5719-llvm-b32c8943e6e03806f81a6e3d7b5a228c89fe746c.zip | |
Have SCEV turn sext(x) into zext(x) when x is s>= 0. This applies many times in
"make check" alone.
llvm-svn: 124046
Diffstat (limited to 'llvm/lib/Analysis')
| -rw-r--r-- | llvm/lib/Analysis/ScalarEvolution.cpp | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/llvm/lib/Analysis/ScalarEvolution.cpp b/llvm/lib/Analysis/ScalarEvolution.cpp index 424f74427be..63602ffaa78 100644 --- a/llvm/lib/Analysis/ScalarEvolution.cpp +++ b/llvm/lib/Analysis/ScalarEvolution.cpp @@ -1035,6 +1035,10 @@ const SCEV *ScalarEvolution::getSignExtendExpr(const SCEV *Op, void *IP = 0; if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S; + // If the input value is provably positive, build a zext instead. + if (isKnownNonNegative(Op)) + return getZeroExtendExpr(Op, Ty); + // If the input value is a chrec scev, and we can prove that the value // did not overflow the old, smaller, value, we can sign extend all of the // operands (often constants). This allows analysis of something like |
