diff options
| author | Francis Visoiu Mistrih <francisvm@yahoo.com> | 2019-04-23 21:57:46 +0000 |
|---|---|---|
| committer | Francis Visoiu Mistrih <francisvm@yahoo.com> | 2019-04-23 21:57:46 +0000 |
| commit | 1646851b87cfe131eb79f2a1302aa5db201bacb6 (patch) | |
| tree | 89b19333c6c72f73f22dd4720d26b4fdae998231 | |
| parent | eea9da5921de502e342469a06856198486e3995d (diff) | |
| download | bcm5719-llvm-1646851b87cfe131eb79f2a1302aa5db201bacb6.tar.gz bcm5719-llvm-1646851b87cfe131eb79f2a1302aa5db201bacb6.zip | |
[CGP] Look through bitcasts when duplicating returns for tail calls
The simple case of:
```
int *callee();
void *caller(void *a) {
if (a == NULL)
return callee();
return a;
}
```
would generate a regular call instead of a tail call because we don't
look through the bitcast of the call to `callee` when duplicating the
return blocks.
Differential Revision: https://reviews.llvm.org/D60837
llvm-svn: 359041
| -rw-r--r-- | llvm/lib/CodeGen/CodeGenPrepare.cpp | 4 | ||||
| -rw-r--r-- | llvm/test/CodeGen/X86/tailcall-cgp-dup.ll | 17 |
2 files changed, 10 insertions, 11 deletions
diff --git a/llvm/lib/CodeGen/CodeGenPrepare.cpp b/llvm/lib/CodeGen/CodeGenPrepare.cpp index 544f9985446..4335f10117e 100644 --- a/llvm/lib/CodeGen/CodeGenPrepare.cpp +++ b/llvm/lib/CodeGen/CodeGenPrepare.cpp @@ -2032,7 +2032,9 @@ bool CodeGenPrepare::dupRetToEnableTailCallOpts(BasicBlock *BB, bool &ModifiedDT SmallVector<CallInst*, 4> TailCalls; if (PN) { for (unsigned I = 0, E = PN->getNumIncomingValues(); I != E; ++I) { - CallInst *CI = dyn_cast<CallInst>(PN->getIncomingValue(I)); + // Look through bitcasts. + Value *IncomingVal = PN->getIncomingValue(I)->stripPointerCasts(); + CallInst *CI = dyn_cast<CallInst>(IncomingVal); // Make sure the phi value is indeed produced by the tail call. if (CI && CI->hasOneUse() && CI->getParent() == PN->getIncomingBlock(I) && TLI->mayBeEmittedAsTailCall(CI) && diff --git a/llvm/test/CodeGen/X86/tailcall-cgp-dup.ll b/llvm/test/CodeGen/X86/tailcall-cgp-dup.ll index cd1d15944cb..fd6bb4c9577 100644 --- a/llvm/test/CodeGen/X86/tailcall-cgp-dup.ll +++ b/llvm/test/CodeGen/X86/tailcall-cgp-dup.ll @@ -118,21 +118,18 @@ define i8* @f_ret8(i8* %obj) nounwind { ; OPT: if.then: ; OPT-NEXT: [[PTR:%.*]] = tail call i32* @g_ret32() ; OPT-NEXT: [[CASTED:%.*]] = bitcast i32* [[PTR]] to i8* -; OPT-NEXT: br label [[RETURN]] +; OPT-NEXT: ret i8* [[CASTED]] ; OPT: return: -; OPT-NEXT: [[RETVAL:%.*]] = phi i8* [ [[CASTED]], [[IF_THEN]] ], [ [[OBJ]], [[ENTRY:%.*]] ] -; OPT-NEXT: ret i8* [[RETVAL]] +; OPT-NEXT: ret i8* [[OBJ]] ; ; CHECK-LABEL: f_ret8: ; CHECK: ## %bb.0: ## %entry -; CHECK-NEXT: movq %rdi, %rax ; CHECK-NEXT: testq %rdi, %rdi -; CHECK-NEXT: je LBB3_2 -; CHECK-NEXT: ## %bb.1: ## %if.then -; CHECK-NEXT: pushq %rax -; CHECK-NEXT: callq _g_ret32 -; CHECK-NEXT: addq $8, %rsp -; CHECK-NEXT: LBB3_2: ## %return +; CHECK-NEXT: je LBB3_1 +; CHECK-NEXT: ## %bb.2: ## %if.then +; CHECK-NEXT: jmp _g_ret32 ## TAILCALL +; CHECK-NEXT: LBB3_1: ## %return +; CHECK-NEXT: movq %rdi, %rax ; CHECK-NEXT: retq entry: %cmp = icmp eq i8* %obj, null |
