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| author | Nick Lewycky <nicholas@mxc.ca> | 2014-05-02 04:11:45 +0000 |
|---|---|---|
| committer | Nick Lewycky <nicholas@mxc.ca> | 2014-05-02 04:11:45 +0000 |
| commit | 26ad3eb69d21232c204e76728936f5845ed67474 (patch) | |
| tree | 0fa5fe6e091dff47b3377284c75d1c609570283c | |
| parent | 30e4655a8aa326c9356a6e44c516b3717ddf771b (diff) | |
| download | llvm-26ad3eb69d21232c204e76728936f5845ed67474.tar.gz llvm-26ad3eb69d21232c204e76728936f5845ed67474.tar.bz2 llvm-26ad3eb69d21232c204e76728936f5845ed67474.tar.xz | |
Fold strlen(expr ? "str1" : "str2") to x ? len1 : len2. This fires about 330 times in a bootstrap of clang.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207828 91177308-0d34-0410-b5e6-96231b3b80d8
| -rw-r--r-- | lib/Transforms/Utils/SimplifyLibCalls.cpp | 15 | ||||
| -rw-r--r-- | test/Transforms/InstCombine/strlen-1.ll | 12 |
2 files changed, 27 insertions, 0 deletions
diff --git a/lib/Transforms/Utils/SimplifyLibCalls.cpp b/lib/Transforms/Utils/SimplifyLibCalls.cpp index 903fbb5899..0fd185816f 100644 --- a/lib/Transforms/Utils/SimplifyLibCalls.cpp +++ b/lib/Transforms/Utils/SimplifyLibCalls.cpp @@ -784,10 +784,25 @@ struct StrLenOpt : public LibCallOptimization { if (uint64_t Len = GetStringLength(Src)) return ConstantInt::get(CI->getType(), Len-1); + // strlen(x?"foo":"bars") --> x ? 3 : 4 + if (SelectInst *SI = dyn_cast<SelectInst>(Src)) { + uint64_t LenTrue = GetStringLength(SI->getTrueValue()); + uint64_t LenFalse = GetStringLength(SI->getFalseValue()); + if (LenTrue && LenFalse) { + Context->emitOptimizationRemark( + "simplify-libcalls", *Caller, SI->getDebugLoc(), + "folded strlen(select) to select of constants"); + return B.CreateSelect(SI->getCondition(), + ConstantInt::get(CI->getType(), LenTrue-1), + ConstantInt::get(CI->getType(), LenFalse-1)); + } + } + // strlen(x) != 0 --> *x != 0 // strlen(x) == 0 --> *x == 0 if (isOnlyUsedInZeroEqualityComparison(CI)) return B.CreateZExt(B.CreateLoad(Src, "strlenfirst"), CI->getType()); + return nullptr; } }; diff --git a/test/Transforms/InstCombine/strlen-1.ll b/test/Transforms/InstCombine/strlen-1.ll index 4fa5b4fdb6..4a3caf28a0 100644 --- a/test/Transforms/InstCombine/strlen-1.ll +++ b/test/Transforms/InstCombine/strlen-1.ll @@ -5,6 +5,7 @@ target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:128:128" @hello = constant [6 x i8] c"hello\00" +@longer = constant [7 x i8] c"longer\00" @null = constant [1 x i8] zeroinitializer @null_hello = constant [7 x i8] c"\00hello\00" @nullstring = constant i8 0 @@ -85,6 +86,17 @@ define i1 @test_simplify8() { ; CHECK-NEXT: ret i1 false } +define i32 @test_simplify9(i1 %x) { +; CHECK-LABEL: @test_simplify9 + %hello = getelementptr [6 x i8]* @hello, i32 0, i32 0 + %longer = getelementptr [7 x i8]* @longer, i32 0, i32 0 + %s = select i1 %x, i8* %hello, i8* %longer + %l = call i32 @strlen(i8* %s) +; CHECK-NEXT: select i1 %x, i32 5, i32 6 + ret i32 %l +; CHECK-NEXT: ret +} + ; Check cases that shouldn't be simplified. define i32 @test_no_simplify1() { |