Index: lib/Target/ARM/ARMFrameLowering.cpp =================================================================== --- lib/Target/ARM/ARMFrameLowering.cpp +++ lib/Target/ARM/ARMFrameLowering.cpp @@ -1746,6 +1746,12 @@ ARMFunctionInfo *ARMFI = MF.getInfo(); DebugLoc DL; + uint64_t StackSize = MFI->getStackSize(); + + // Do not generate a prologue for functions with a stack of size zero + if (StackSize == 0) + return; + // Use R4 and R5 as scratch registers. // We save R4 and R5 before use and restore them before leaving the function. unsigned ScratchReg0 = ARM::R4; @@ -1775,8 +1781,6 @@ MF.push_front(PrevStackMBB); // The required stack size that is aligned to ARM constant criterion. - uint64_t StackSize = MFI->getStackSize(); - AlignedStackSize = alignToARMConstant(StackSize); // When the frame size is less than 256 we just compare the stack Index: lib/Target/X86/X86FrameLowering.cpp =================================================================== --- lib/Target/X86/X86FrameLowering.cpp +++ lib/Target/X86/X86FrameLowering.cpp @@ -1176,6 +1176,15 @@ !STI.isTargetWin32() && !STI.isTargetWin64() && !STI.isTargetFreeBSD()) report_fatal_error("Segmented stacks not supported on this platform."); + // Eventually StackSize will be calculated by a link-time pass; which will + // also decide whether checking code needs to be injected into this particular + // prologue. + StackSize = MFI->getStackSize(); + + // Do not generate a prologue for functions with a stack of size zero + if (StackSize == 0) + return; + MachineBasicBlock *allocMBB = MF.CreateMachineBasicBlock(); MachineBasicBlock *checkMBB = MF.CreateMachineBasicBlock(); X86MachineFunctionInfo *X86FI = MF.getInfo(); @@ -1200,11 +1209,6 @@ MF.push_front(allocMBB); MF.push_front(checkMBB); - // Eventually StackSize will be calculated by a link-time pass; which will - // also decide whether checking code needs to be injected into this particular - // prologue. - StackSize = MFI->getStackSize(); - // When the frame size is less than 256 we just compare the stack // boundary directly to the value of the stack pointer, per gcc. bool CompareStackPointer = StackSize < kSplitStackAvailable; Index: test/CodeGen/ARM/segmented-stacks.ll =================================================================== --- test/CodeGen/ARM/segmented-stacks.ll +++ test/CodeGen/ARM/segmented-stacks.ll @@ -57,6 +57,8 @@ define i32 @test_nested(i32 * nest %closure, i32 %other) #0 { %addend = load i32 * %closure %result = add i32 %other, %addend + %mem = alloca i32, i32 10 + call void @dummy_use (i32* %mem, i32 10) ret i32 %result ; ARM-linux: test_nested: @@ -68,7 +70,7 @@ ; ARM-linux-NEXT: cmp r4, r5 ; ARM-linux-NEXT: blo .LBB1_2 -; ARM-linux: mov r4, #0 +; ARM-linux: mov r4, #56 ; ARM-linux-NEXT: mov r5, #0 ; ARM-linux-NEXT: stmdb sp!, {lr} ; ARM-linux-NEXT: bl __morestack @@ -87,7 +89,7 @@ ; ARM-android-NEXT: cmp r4, r5 ; ARM-android-NEXT: blo .LBB1_2 -; ARM-android: mov r4, #0 +; ARM-android: mov r4, #56 ; ARM-android-NEXT: mov r5, #0 ; ARM-android-NEXT: stmdb sp!, {lr} ; ARM-android-NEXT: bl __morestack @@ -234,4 +236,14 @@ } +define void @test_nostack() #0 { + ret void + +; ARM-linux-LABEL: test_nostack: +; ARM-linux-NOT: bl __morestack + +; ARM-android-LABEL: test_nostack: +; ARM-android-NOT: bl __morestack +} + attributes #0 = { "split-stack" } Index: test/CodeGen/Thumb/segmented-stacks.ll =================================================================== --- test/CodeGen/Thumb/segmented-stacks.ll +++ test/CodeGen/Thumb/segmented-stacks.ll @@ -57,6 +57,8 @@ define i32 @test_nested(i32 * nest %closure, i32 %other) #0 { %addend = load i32 * %closure %result = add i32 %other, %addend + %mem = alloca i32, i32 10 + call void @dummy_use (i32* %mem, i32 10) ret i32 %result ; Thumb-android: test_nested: @@ -68,7 +70,7 @@ ; Thumb-android-NEXT: cmp r4, r5 ; Thumb-android-NEXT: blo .LBB1_2 -; Thumb-android: mov r4, #0 +; Thumb-android: mov r4, #56 ; Thumb-android-NEXT: mov r5, #0 ; Thumb-android-NEXT: push {lr} ; Thumb-android-NEXT: bl __morestack @@ -88,7 +90,7 @@ ; Thumb-linux-NEXT: cmp r4, r5 ; Thumb-linux-NEXT: blo .LBB1_2 -; Thumb-linux: mov r4, #0 +; Thumb-linux: mov r4, #56 ; Thumb-linux-NEXT: mov r5, #0 ; Thumb-linux-NEXT: push {lr} ; Thumb-linux-NEXT: bl __morestack @@ -246,4 +248,14 @@ } +define void @test_nostack() #0 { + ret void + +; Thumb-android-LABEL: test_nostack: +; Thumb-android-NOT: bl __morestack + +; Thumb-linux-LABEL: test_nostack: +; Thumb-linux-NOT: bl __morestack +} + attributes #0 = { "split-stack" } Index: test/CodeGen/X86/segmented-stacks.ll =================================================================== --- test/CodeGen/X86/segmented-stacks.ll +++ test/CodeGen/X86/segmented-stacks.ll @@ -107,13 +107,15 @@ define i32 @test_nested(i32 * nest %closure, i32 %other) #0 { %addend = load i32 * %closure %result = add i32 %other, %addend + %mem = alloca i32, i32 10 + call void @dummy_use (i32* %mem, i32 10) ret i32 %result ; X32-Linux: cmpl %gs:48, %esp ; X32-Linux-NEXT: ja .LBB1_2 ; X32-Linux: pushl $4 -; X32-Linux-NEXT: pushl $0 +; X32-Linux-NEXT: pushl $60 ; X32-Linux-NEXT: calll __morestack ; X32-Linux-NEXT: ret @@ -121,7 +123,7 @@ ; X64-Linux-NEXT: ja .LBB1_2 ; X64-Linux: movq %r10, %rax -; X64-Linux-NEXT: movabsq $0, %r10 +; X64-Linux-NEXT: movabsq $56, %r10 ; X64-Linux-NEXT: movabsq $0, %r11 ; X64-Linux-NEXT: callq __morestack ; X64-Linux-NEXT: ret @@ -132,7 +134,7 @@ ; X32-Darwin-NEXT: ja LBB1_2 ; X32-Darwin: pushl $4 -; X32-Darwin-NEXT: pushl $0 +; X32-Darwin-NEXT: pushl $60 ; X32-Darwin-NEXT: calll ___morestack ; X32-Darwin-NEXT: ret @@ -140,7 +142,7 @@ ; X64-Darwin-NEXT: ja LBB1_2 ; X64-Darwin: movq %r10, %rax -; X64-Darwin-NEXT: movabsq $0, %r10 +; X64-Darwin-NEXT: movabsq $56, %r10 ; X64-Darwin-NEXT: movabsq $0, %r11 ; X64-Darwin-NEXT: callq ___morestack ; X64-Darwin-NEXT: ret @@ -150,7 +152,7 @@ ; X32-MinGW-NEXT: ja LBB1_2 ; X32-MinGW: pushl $4 -; X32-MinGW-NEXT: pushl $0 +; X32-MinGW-NEXT: pushl $52 ; X32-MinGW-NEXT: calll ___morestack ; X32-MinGW-NEXT: ret @@ -159,7 +161,7 @@ ; X64-MinGW-NEXT: ja .LBB1_2 ; X64-MinGW: movq %r10, %rax -; X64-MinGW-NEXT: movabsq $0, %r10 +; X64-MinGW-NEXT: movabsq $88, %r10 ; X64-MinGW-NEXT: movabsq $32, %r11 ; X64-MinGW-NEXT: callq __morestack ; X64-MinGW-NEXT: retq @@ -169,7 +171,7 @@ ; X64-FreeBSD-NEXT: ja .LBB1_2 ; X64-FreeBSD: movq %r10, %rax -; X64-FreeBSD-NEXT: movabsq $0, %r10 +; X64-FreeBSD-NEXT: movabsq $56, %r10 ; X64-FreeBSD-NEXT: movabsq $0, %r11 ; X64-FreeBSD-NEXT: callq __morestack ; X64-FreeBSD-NEXT: ret @@ -435,4 +437,29 @@ } +define void @test_nostack() #0 { + ret void + +; X32-Linux-LABEL: test_nostack: +; X32-Linux-NOT: calll __morestack + +; X64-Linux-LABEL: test_nostack: +; X32-Linux-NOT: callq __morestack + +; X32-Darwin-LABEL: test_nostack: +; X32-Darwin-NOT: calll __morestack + +; X64-Darwin-LABEL: test_nostack: +; X64-Darwin-NOT: callq __morestack + +; X32-MinGW-LABEL: test_nostack: +; X32-MinGW-NOT: calll __morestack + +; X64-MinGW-LABEL: test_nostack: +; X64-MinGW-NOT: callq __morestack + +; X64-FreeBSD-LABEL: test_nostack: +; X64-FreeBSD-NOT: callq __morestack +} + attributes #0 = { "split-stack" }