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A branch predicated on a constant can just FastEmit an unconditional branch. 

llvm-svn: 143086
This commit is contained in:
Chad Rosier 2011-10-27 00:21:16 +00:00
parent a9aabf7d51
commit d24e7e1d9b
2 changed files with 53 additions and 0 deletions
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6
llvm/lib/Target/ARM/ARMFastISel.cpp
View File

@ -1151,6 +1151,12 @@ bool ARMFastISel::SelectBranch(const Instruction *I) {
FuncInfo.MBB->addSuccessor(TBB); FuncInfo.MBB->addSuccessor(TBB);
return true; return true;
} }
} else if (const ConstantInt *CI =
dyn_cast<ConstantInt>(BI->getCondition())) {
uint64_t Imm = CI->getZExtValue();
MachineBasicBlock *Target = (Imm == 0) ? FBB : TBB;
FastEmitBranch(Target, DL);
return true;
} }
unsigned CmpReg = getRegForValue(BI->getCondition()); unsigned CmpReg = getRegForValue(BI->getCondition());

47
llvm/test/CodeGen/ARM/fast-isel-br-const.ll Normal file
View File

@ -0,0 +1,47 @@
; RUN: llc < %s -O0 -fast-isel-abort -relocation-model=dynamic-no-pic -mtriple=armv7-apple-darwin | FileCheck %s --check-prefix=ARM
; RUN: llc < %s -O0 -fast-isel-abort -relocation-model=dynamic-no-pic -mtriple=thumbv7-apple-darwin | FileCheck %s --check-prefix=THUMB
define i32 @t1(i32 %a, i32 %b) nounwind uwtable ssp {
entry:
; THUMB: t1:
; ARM: t1:
br i1 1, label %if.then, label %if.else
; THUMB-NOT: b LBB0_1
; ARM-NOT: b LBB0_1
if.then: ; preds = %entry
call void @foo1()
br label %if.end7
if.else: ; preds = %entry
br i1 0, label %if.then2, label %if.else3
; THUMB: b LBB0_4
; ARM: b LBB0_4
if.then2: ; preds = %if.else
call void @foo2()
br label %if.end6
if.else3: ; preds = %if.else
br i1 1, label %if.then5, label %if.end
; THUMB-NOT: b LBB0_5
; ARM-NOT: b LBB0_5
if.then5: ; preds = %if.else3
call void @foo1()
br label %if.end
if.end: ; preds = %if.then5, %if.else3
br label %if.end6
if.end6: ; preds = %if.end, %if.then2
br label %if.end7
if.end7: ; preds = %if.end6, %if.then
ret i32 0
}
declare void @foo1()
declare void @foo2()