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ae16d6b972
to have single return block (at least getting there) for optimizations. This is general goodness but it would prevent some tailcall optimizations. One specific case is code like this: int f1(void); int f2(void); int f3(void); int f4(void); int f5(void); int f6(void); int foo(int x) { switch(x) { case 1: return f1(); case 2: return f2(); case 3: return f3(); case 4: return f4(); case 5: return f5(); case 6: return f6(); } } => LBB0_2: ## %sw.bb callq _f1 popq %rbp ret LBB0_3: ## %sw.bb1 callq _f2 popq %rbp ret LBB0_4: ## %sw.bb3 callq _f3 popq %rbp ret This patch teaches codegenprep to duplicate returns when the return value is a phi and where the phi operands are produced by tail calls followed by an unconditional branch: sw.bb7: ; preds = %entry %call8 = tail call i32 @f5() nounwind br label %return sw.bb9: ; preds = %entry %call10 = tail call i32 @f6() nounwind br label %return return: %retval.0 = phi i32 [ %call10, %sw.bb9 ], [ %call8, %sw.bb7 ], ... [ 0, %entry ] ret i32 %retval.0 This allows codegen to generate better code like this: LBB0_2: ## %sw.bb jmp _f1 ## TAILCALL LBB0_3: ## %sw.bb1 jmp _f2 ## TAILCALL LBB0_4: ## %sw.bb3 jmp _f3 ## TAILCALL rdar://9147433 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@127953 91177308-0d34-0410-b5e6-96231b3b80d8 |
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Analysis | ||
Archive | ||
Assembler | ||
Bindings/Ocaml | ||
Bitcode | ||
BugPoint | ||
CodeGen | ||
DebugInfo | ||
ExecutionEngine | ||
Feature | ||
FrontendAda | ||
FrontendC | ||
FrontendC++ | ||
FrontendFortran | ||
FrontendObjC | ||
FrontendObjC++ | ||
Integer | ||
lib | ||
Linker | ||
LLVMC | ||
MC | ||
Object | ||
Other | ||
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TableGen | ||
Transforms | ||
Unit | ||
Verifier | ||
CMakeLists.txt | ||
lit.cfg | ||
lit.site.cfg.in | ||
Makefile | ||
Makefile.tests | ||
site.exp.in | ||
TestRunner.sh |