forked from OSchip/llvm-project
[ARM] Don't shrink STM if it would cause an unknown base register store
If a 16-bit thumb STM with writeback stores the base register but it isn't the first register in the list, then an unknown value is stored. The load/store optimizer knows this and generates a 32-bit STM without writeback instead, but thumb2 size reduction converts it into a 16-bit STM. Fix this by having thumb2 size reduction notice such STMs and leave them as they are. Differential Revision: https://reviews.llvm.org/D78493
This commit is contained in:
John Brawn
John Brawn
parent
41d52662d5
commit
8211cfb7c8
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@ -516,13 +516,23 @@ Thumb2SizeReduce::ReduceLoadStore(MachineBasicBlock &MBB, MachineInstr *MI,
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isLdStMul = true;
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break;
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}
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case ARM::t2STMIA:
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// If the base register is killed, we don't care what its value is after the
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// instruction, so we can use an updating STMIA.
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case ARM::t2STMIA: {
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// t2STMIA is reduced to tSTMIA_UPD which has writeback. We can only do this
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// if the base register is killed, as then it doesn't matter what its value
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// is after the instruction.
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if (!MI->getOperand(0).isKill())
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return false;
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// If the base register is in the register list and isn't the lowest
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// numbered register (i.e. it's in operand 4 onwards) then with writeback
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// the stored value is unknown, so we can't convert to tSTMIA_UPD.
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Register BaseReg = MI->getOperand(0).getReg();
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for (unsigned i = 4; i < MI->getNumOperands(); ++i)
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if (MI->getOperand(i).getReg() == BaseReg)
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return false;
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break;
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}
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case ARM::t2LDMIA_RET: {
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Register BaseReg = MI->getOperand(1).getReg();
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if (BaseReg != ARM::SP)
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@ -1,19 +1,81 @@
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; RUN: llc -mtriple=thumbv6m-eabi -verify-machineinstrs %s -o - | FileCheck %s
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; RUN: llc -mtriple=thumbv5e-linux-gnueabi -verify-machineinstrs %s -o - | FileCheck %s
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; RUN: llc -mtriple=thumbv6m-eabi -verify-machineinstrs %s -o - | FileCheck %s --check-prefixes=CHECK,CHECK-T1
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; RUN: llc -mtriple=thumbv5e-linux-gnueabi -verify-machineinstrs %s -o - | FileCheck %s --check-prefixes=CHECK,CHECK-T1
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; RUN: llc -mtriple=thumbv7m -verify-machineinstrs %s -o - | FileCheck %s --check-prefixes=CHECK,CHECK-T2
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; RUN: llc -mtriple=thumbv7a -verify-machineinstrs %s -o - | FileCheck %s --check-prefixes=CHECK,CHECK-T2
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%0 = type { %0*, %0*, i32 }
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%struct1 = type { %struct1*, %struct1*, i32 }
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%struct2 = type { i32, i32, i32* }
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@x1 = external global %0, align 4
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@x2 = external global %0, align 4
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@x1 = external global %struct1, align 4
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@x2 = external global %struct1, align 4
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; CHECK: str r0, [r1]
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; CHECK-NEXT: str r1, [r1, #4]
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declare void @fn1(i32, i32)
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declare void @fn2(%struct2*)
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; CHECK-LABEL: test1:
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; CHECK-T1: str r0, [r1]
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; CHECK-T1-NEXT: str r1, [r1, #4]
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; CHECK-T2: strd r0, r1, [r1]
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; CHECK-NOT: stm
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define void @foo(i32 %unused, %0* %x) {
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%first = getelementptr inbounds %0, %0* %x, i32 0, i32 0
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%second = getelementptr inbounds %0, %0* %x, i32 0, i32 1
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store %0* @x1, %0** %first
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store %0* %x, %0** %second
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unreachable
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define void @test1(i32 %unused, %struct1* %x) {
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%first = getelementptr inbounds %struct1, %struct1* %x, i32 0, i32 0
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%second = getelementptr inbounds %struct1, %struct1* %x, i32 0, i32 1
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store %struct1* @x1, %struct1** %first
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store %struct1* %x, %struct1** %second
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ret void
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}
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; CHECK-LABEL: test2:
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; CHECK-T1: str r0, [r2]
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; CHECK-T1-NEXT: str r1, [r2, #4]
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; CHECK-T1-NEXT: str r2, [r2, #8]
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; CHECK-T2: stm.w r2, {r0, r1, r2}
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; CHECK-NOT: stm r2!, {r0, r1, r2}
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define i32 @test2(i32 %a, i32 %b, %struct2* %p) {
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entry:
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%p1 = getelementptr inbounds %struct2, %struct2* %p, i32 0, i32 0
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%p2 = getelementptr inbounds %struct2, %struct2* %p, i32 0, i32 1
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%p3 = getelementptr inbounds %struct2, %struct2* %p, i32 0, i32 2
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store i32 %a, i32* %p1, align 4
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store i32 %b, i32* %p2, align 4
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store i32* %p1, i32** %p3, align 4
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call void @fn1(i32 %a, i32 %b)
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ret i32 0
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}
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; CHECK-LABEL: test3:
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; CHECK-T1: str r0, [r2]
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; CHECK-T1-NEXT: str r1, [r2, #4]
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; CHECK-T1-NEXT: str r2, [r2, #8]
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; CHECK-T2: stm.w r2, {r0, r1, r2}
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; CHECK-NOT: stm r2!, {r0, r1, r2}
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define i32 @test3(i32 %a, i32 %b, %struct2* %p) {
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entry:
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%p1 = getelementptr inbounds %struct2, %struct2* %p, i32 0, i32 0
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%p2 = getelementptr inbounds %struct2, %struct2* %p, i32 0, i32 1
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%p3 = getelementptr inbounds %struct2, %struct2* %p, i32 0, i32 2
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store i32 %a, i32* %p1, align 4
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store i32 %b, i32* %p2, align 4
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store i32* %p1, i32** %p3, align 4
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%p4 = getelementptr inbounds %struct2, %struct2* %p, i32 1
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call void @fn2(%struct2* %p4)
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ret i32 0
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}
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; FIXME: We should be using stm in both thumb1 and thumb2
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; CHECK-LABEL: test4:
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; CHECK-T1: str r0, [r0]
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; CHECK-T1-NEXT: str r1, [r0, #4]
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; CHECK-T1-NEXT: str r2, [r0, #8]
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; CHECK-T2: stm r0!, {r0, r1, r2}
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define i32 @test4(%struct1* %p, %struct1* %q, i32 %a) {
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entry:
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%p1 = getelementptr inbounds %struct1, %struct1* %p, i32 0, i32 0
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%p2 = getelementptr inbounds %struct1, %struct1* %p, i32 0, i32 1
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%p3 = getelementptr inbounds %struct1, %struct1* %p, i32 0, i32 2
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store %struct1* %p, %struct1** %p1, align 4
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store %struct1* %q, %struct1** %p2, align 4
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store i32 %a, i32* %p3, align 4
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call void @fn1(i32 %a, i32 %a)
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ret i32 0
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}
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