runtime: softfloat emulation doesn't support conditional execution #3638
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0x159fb010 is "ldrne fp, [pc, #16]" unfortunately the softfloat emulator doesn't handle conditional execution of instructions. The surrounding instructions are: 6d010: 159fb010 ldrne fp, [pc, #16] ; 6d028 <_ul2d+0x70> 6d014: 1d9b2a00 vldrne s4, [fp] 6d018: 1e311a02 vaddne.f32 s2, s2, s4 6d01c: eeb00b41 vmov.f64 d0, d1 6d020: e28ef000 add pc, lr, #0 Three of them are all conditional, so we must support conditional execution in stepflt(), this will take some time, for I must verify that all the instruction executed by it supports conditional execution (although I think so). A temp. workaround is to disable optimizer in 5c again in softfloat builds. (add "debug['N'] = 1;" to main() in cc/lex.c:L96 after "memset(debug, 0, sizeof(debug));".) I will tackle the general problem. Should we setup a soft float ARMv5 builder to avoid introduce these kind of bugs latter? (I have a custom built qemu-system-arm without VFP support, but it took 2 hours to run make.bash and 'go test -short std') Labels changed: added priority-later, removed priority-triage. |
http://golang.org/cl/6213057 Status changed to Started. |
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This issue was closed by revision fb3a1b6. Status changed to Fixed. |
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May 11, 2015
…ftfloat
««« backport 87ef5e0baaf5
runtime: support conditional execution in ARM softfloat
Fixes #3638.
R=golang-dev, dave, rsc
CC=golang-dev
https://golang.org/cl/6213057
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What steps will reproduce the problem? My arm5 host is slowly ceasing to be able to build Go normally (at some point I will have to switch to cross compiling from another arm system), however after doing a successful ./make.bash it looks like there is a problem in the softfloat emulation. stora(~/go/src) % go test -v std sfloat2 0x71924 0x159fb010 Unsupported floating point instruction panic: runtime error: invalid memory address or nil pointer dereference [signal 0xb code=0x1 addr=0x0 pc=0x7624c] goroutine 3 [running]: created by main.(*builder).do /home/dfc/go/src/cmd/go/build.go:608 +0x53c goroutine 1 [chan receive]: main.(*builder).do(0x10db72c0, 0x10ce7770, 0x10963dc0) /home/dfc/go/src/cmd/go/build.go:611 +0x568 main.runTest(0x456f90, 0x1094d410, 0x2) /home/dfc/go/src/cmd/go/test.go:367 +0x24b8 main.main() /home/dfc/go/src/cmd/go/main.go:141 +0x5c8 goroutine 2 [syscall]: created by runtime.main /home/dfc/go/src/pkg/runtime/proc.c:221 goroutine 10 [syscall]: created by addtimer /home/dfc/go/src/pkg/runtime/ztime_linux_arm.c:69The text was updated successfully, but these errors were encountered: